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The "Official" Evo Modding for Dummies

Old Mar 5, 2008, 11:45 PM
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The "Official" Evo Modding for Dummies

So you decided you want to modify your Evo?

This thread is dedicated to helping you learn the basics and choose the parts that are right for you.

I am by no means an expert when it comes to these cars. This is all my opinion. I have had a few setups on my car and I have read numerous threads as well as reviewing time slips and dyno sheets on others' cars.

This is merely a guide to help anyone that doesn't know anything in regards to what works and what doesn't.

**I made this to help eliminate the "what mods should I do to my evo?" threads.**
**If you guys have anything you'd like to add just PM me (I'll give you the credit.)**


Thanks to Recompile for a well written information thread found here:

Basic Bolt on Mods:

Turbo-back Exhaust (TBE):
This is one of the most common and most rewarding starting points when it comes to modding. Turbo back means you are changing your dowpipe/cat/midpipe/catback. Adding a full exhaust will open up the airways so your turbo breathes more easily.

Evom has plenty of vendors that offer multiple exhaust combos so you have the ability to pick and choose what you are looking for.

- Evos with ACD require a different downpipe than Evos without ACD (fitment issues)
- As far replacing the catalytic converter is concerned (For off-road use only of course): You can use a straight through test pipe/high flow cat/resonated test pipe.
- 3" is the standard among aftermarket exhaust replacements.
- All exhaust will yield different gains based on design and pipe diameter.
- A re-tune is required to make higher gains out of an exhaust.

Boost Controller (MBC/EBC):

You have two main options when it comes to boost controllers. First, a manual boost controller. Second, an electronic boost controller. The purpose of this mod is to allow you to control your boost and yield higher gains. DO NOT ADJUST TO HIGHER THAN STOCK BOOST WITHOUT A TUNE!!!

Manual boost controller (MBC): They have a simple design and require no wiring what-so-ever. All that is involved in them is rerouting vacuum lines. They will decrease boost taper and give you full adjust ability over the boost of your turbo. You will need a boost gauge or data-logging equipment to check your boost.

Electronic boost controller (EBC): They are obviously electronic and require a little more setup time. They allow you to dial in your boost more accurately and some allow more than one preset setting (ex: high and low boost). They also compensate for changes in weather (density of the air) and are less likely to experience boost creep in the cold.

- MBC are much cheaper and have only one working part.
- EBC can cost as much as four times what an MBC costs but provide better adjust ability and more precise control. They adapt to weather and allow for multiple settings.

Boost Gauge:

The purpose of a boost gauge is obvious; monitor your boost level. You can get manual boost gauges or electronic ones; same concept as MBC's/EBC's. Cost and accuracy are factors here. This is a very necessary mod and not having it is similar to playing with knives blindfolded.

- Helps with tuning.
- Available with and without vacuum readings

Wideband - Air/Fuel Ratio Gauge

The purpose of an AFR gauge is to monitor the ratio of air/fuel to 1. This allows self tuners and pro tuners to tune a car to it's maximum level. They are primarily digital and require being welded into the downpipe of the vehicle.

- Aside from a boost gauge this is the most important gauge to have
- Most commonly used is an AEM UEGO AFR gauge
- Vital to tuning
- The higher the number the leaner the air/fuel mixture is
- The lower the number the more rich the mixture is
- 12:1 is pretty much as high as you want to see at WOT
- 14/15:1 is average for spooling
- 14/15: is also average for idle
- If the car runs rich it will foul spark plugs quickly
- If the car is lean it will pull timing and possibly knock

Fuel Pump:

Upgrading your fuel pump is a cheap mod and can save you an engine in the long run. They are inexpensive and allow you to up the boost since the amount of fuel can be upped with the boost.

- VIII's had a less capable fuel pumps than IX's do.
- VIII - 300whp or more the pump should be changed out (just my opinion)
- IX - 350whp or more the pump should be changed out (just my opinion)
- 99 out of 100 people use a Walbro 255lph fuel pump; it is a drop in replacement.
- A tune is needed to make full use of an upgraded fuel pump.


Many will tell you that a stock intake box with a drop in element is your best bet. This solution is good up until about 400whp. There is nothing wrong with that solution but an open filter intake will yield gains. Some open filters use the stock intake pipe some require their own. When upgrading the intake a tune is very important. Especially if you eliminate the stock rubber intake pipe and substitute it for a metal one. The intake pipe wreaks havoc on your MAF readings and cause a jumpy idle. They can even cause the car to stall in certain situations.

- Some open filters are dry and some require oiling.
- If you replace the factory intake pipe, be prepared to deal with an erratic idle.
- A tune is needed to see gains and improve drive ability.

Diverter Valve/ Blow Off Valve (DV/BOV):

Do yourself a favor; kill the ricer within you now. Evos do not respond well to BOVs. Especially if they vent 100% atmospherically. The stock IX diverter valve (aka JDM MR diverter valve) is a very capable and inexpensive solution. The IX diverter is metal and can handle 25 psi without any issue. You will experience very limited, if any drive ability issues. Partial throttle situations will be manageable and not violent.

- If you have an VIII, do yourself a favor and get a IX diverter valve.
- Don't be a ricer, unless you have an aftermarket ecu then stick with a recirculated diverter.
- Aftermarket diverters tend to have partial throttle issues and will never be as daily driving friendly as the stock IX diverter.

Intercooler (FMIC):

The stock FMIC is very well matched to the stock turbo and really doesn't need to be upgraded. However, a 3" FMIC will decrease the chances of heat soak and provide some minimal gains.

- Not much to say here.

Intercooler Piping (UICP/LICP):

The upper intercooler piping (UICP) isn't going to do much in terms of gains but it will limit you to a stock flanged DV/BOV. The lower intercooler pipe is a great mod. It will improve spool up. Reason being, the stock LICP tapers towards the turbo and has unnecessary bends.

- UICP: Not really a necessary mod unless you need a different flange or you are using a mini battery and have the room to use a shorter route UCIP.
- LICP: Definitely a great mod, you'll see HP/TQ gains as well as quicker spool up.
- It's not a bad idea to upgrade the stock pipe couplings. They tend to expand under boost.

O2 Housing:

An O2 housing is what the downpipe on the exhaust bolts to. The idea is the same as the TBE; open up the exhaust to increase hp/tq ratings as well as improve spool up time. This mod requires a bit of time and disassembly.

- You can get them ported and coated to retain heat.
- Can cause boost creep because of how much they open up the exhaust.

Under Hood Shifter Bushing:

Sure, they won't make your car faster but they will make it more enjoyable. The shifter feel in an Evo leaves something to be desired. These bad boys are the solution. They'll eliminate the sloppy feel of the shifter and help make your shifts feel much more precise.

- They will also help eliminate high RPM lock out some aftermarket clutches can cause.
- Cheap mod and well worth it.


The most common method of tuning these cars now a days is a simple reflash. Evos have a few programs available for download that have tons of logging parameters and can be used to log and tune these cars. Any evo tuner can do this for you or you can do everything yourself with a laptop/Tactix cable/programs. You can get the car street tuned or dyno tuned. Either way, a tune is the true way to unlock the potential of an Evo. It gets you the most out of your mods and allows proper adjustment for fuel/boost/etc. Bottom line, GET A TUNE!!!

- I only mentioned a reflash because it is the most sensible option for someone new to modding
- Search the forums for tuners in your area or those that offer mail in flashes.
- Increases power as well as gas mileage.

Methanol Injection:

Basically this is an alcohol container with a pump attached to it not so unlike your windshield fluid tank. These devices are usually preset to come on during some kind of trigger say... boost, throttle position, or maybe even a combination. What they do is flow methanol or some other alcohol into the intake stream via a nozzle. You can buy nozzles of different sizes to increase the amount of fuel flowing in. What this does is not only add additional fuel to the engine so your injectors will work less but increases the octane rating because methanol and ethanol both have much higher octane ratings than standard pump fuel. An additional side effect is the intake charge temperature is lowered due to the evaporation of the alcohol, just like when you get some rubbing alcohol on your hands and it feels cold same effect.

If you plan on getting one of these kits make sure you get a tune. A stock Evo already runs very very rich and by adding more fuel your only going to make it worse.

Water Injection:

Water injection is by all means absolutely the same idea as methanol injection but water does not provide additional fuel nor does it provide additional octane. The reason people do this is the combustion chamber contains a lot of residual heat left behind by the burn. The water enters the chamber and rapidly cools down the air in the chamber allowing you to run more boost and more timing but the downfall is the octane is still limited so it will not be as effective at controlling detonation.

Stock Frame Turbos:

I think a stock-framed turbo upgrade would fit within the general classification of "bolt-on upgrades" - after all, a turbo is not particularly difficult to remove/install, and it DOES bolt on without any additional parts/changes, other than a remap of the ECU and possibly larger injectors/bigger fuel pump.

The benefits of stock-frame turbo upgrades are:

- spool characteristics similar to the OEM Mitsubishi turbo
- lower cost of entry
- easy/simple installation
- OEM-like appearance, if you're into having an engine compartment that looks stock

A few easy, popular options:

FP White
FP Green
FP Red
CBRD BBK (full and lite)
Tomei Arms

Of course, it is up to the individual Evo owner to decide which turbo upgrade option is best for them... there's always a tradeoff between quick spool and fast transient response vs. ultimate top-end power.

Beyond bolt on mods:

All Courtesy of RoadSpike

Built Block:

This means that the lower end (rods, pistons, and sometimes the crank) have been replaced with high strength forged parts capable of taking additional abuse. These stronger parts will allow the motor to rev higher as well as take the increased power output of high output turbos like the gt42r even when pushing to or above 1000whp.

Stroker Kit:

The stroker kit increases the displacement of your motor by increasing the stroke or rotating size of the crank. These kits include a complete rotating assembly (pistons, rods, crank). Stroker kits increase the torque output of the motor due to its increased size but limit the safe rev limit of the motor when compared to built motors with the stock crank.

Head Work:

The most basic mod to your stock Evo head would be to put upgraded springs and retainers into it. This increases the safe rev limit of the head preventing valve float, where the valves don't properly seat in high rpm operation due to low spring pressure. This of course is assuming your bottom end will take the abuse the stock bottom end isn't known to be very reliable beyond 8k rpm. Additionally to springs you can opt to have your head port and polished. This means that the heads will be gasket port matched so the opening to the head is the exact size of the gasket creating a smooth transition and increasing overall flow. The last thing done to heads is the use of oversize valves. Over sized valves allow for large valve openings which again increase over all flow of the head.


Generally thought of as one of the best bang for the buck mods cams increase the power of the motor by allowing the motor to breathe more efficiently at some rpm range. Cams are measured by lift, how high the valve is opened, and by the duration which means the amount of time the valve stays open. There is also another measurement called ramp rate which is the speed in which the valve opens or closes. Stock valve trains can only safely lift the valves 10.5m to 10.8mm at mild ramp rates as seen in the hks and gsc s1 cams. Aggressive cams like the JUN 272's require the use of aftermarket springs to account for the high ramp rates and lifts the cams produce.

Besides the obvious number on the cam 264 and so on you need to consider the valve lift the cams produce. It should seem pretty obvious that if you lift up the valves more then more air will rush into the chamber. Now combine that with how fast they open and how long they say open for and you'll get an idea why some cams like the JUN 272 are VERY AGGRESSIVE and why the HKS 272's are not.

Defining Aggressive:

Lets use the GSC "S" series cams as the example here for how duration and lift effects the power. With the S1 cams you have a 268/266 cam combo with just 10.5 mm lift this cam would be effective from 3000-8000rpms. The S2 cams have even larger lifts (11.2/11.1) and durations (274/272) making them quite aggressive pushing the power band to the right 4000-9000rpms. S3 cams have what i consider insane lift (11.5mm) and large durations (290 or 280) making their application strictly geared towards all out power, don't expect these to idle with no effort.

As you make the cam more and more aggressive what happens is at very low engine speed ,IE idle, you start to loose running vacuum. This is because of valve overlap which means simply the duration of time when the exhaust valve is still open and the intake is opening. Some where in the 20's or 30's some genius figured out if you open the valves when the exhaust is being pulled out it improves performance however if you do this too much then your idle suffers since the charge of air will be diminished if you leave the exhaust valve open for too long air escapes out into the exhaust. However on the flip side at higher rpm overlap helps improve the air charge into the combustion chamber making more power.

Now you may believe that HKS 272's are aggressive based on the S2 specs but really they aren't because the lifts they produce are much less than a S2 cam. The lift of HKS is 10.8mm intake and 10.2mm exhaust, this shows it has higher lift than a s1 on the intake making the intake more aggressive and lower lift on the exhaust making it less aggressive there. This kind of combination would make less midrange power but come into range at slightly higher rpm ranges than the S1 cams. Now as a curve ball the JUN 272's are very aggressive with lifts around or maybe even higher then the S2 cams making their power band along the lines of the s2 cams. If your purchasing cams from a shop and your confused as to how aggressive they are I suggest just calling them and asking them questions.

Cam Selection:

If you plan on sticking with a turbo from stock up to gt30r series then the kind of cam selection that would benefit you the most would be a moderate to very light cam in terms of aggressiveness. There are many cams out there anything along the lines of hks 272/264, S1, or some other lower lift 272's out there would be fine.

If you plan on stepping up the turbo to a gt35r and beyond then larger cams will certainly add power in those turbo's effective ranges 4k+ rpms. If you plan on trying to beat the current HP records then maybe the S3 cams are right for you

The only other notes i can give is that the larger the duration of the cam then the larger the overlap will be and thus your idle will need more adjusting. If your going for aggressive cams your going to need to get a tuner to help you dial them in.

Cam Gears:

The idea behind cam gears is very simple, basically what your doing with cam gears is changing either the center location of the cams, the overlap, or both. So with the gears you can fine tune your cams shifting the power band from left to right but usually at the cost of performance somewhere else.

continued in next post...

Last edited by chaotichoax; Feb 14, 2011 at 10:33 PM.
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Old Mar 5, 2008, 11:53 PM
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Suspension mods:

Courtesy of RoadSpike & EGbeater

Coil Overs:

Coil overs are by definition are an aftermarket item that combines both the spring and shock absorber in one adjustable unit. The adjustments a typical coilover will allow you to make are ride height with the form of adjustable nuts around the coilover and an adjustment to compression/rebound. The rebound/compression nob usually found on the top of the coil overs adjust how stiff your ride will be the lower you put the car the stiffer the ride must become or you will risk bottoming out the car and perhaps causing damage.

Anti-sway/roll stabilizer Bars

Anti-sway bars (also known as anti-roll bars) are used along with shock absorbers or struts to give a moving automobile additional stability. An anti-sway bar is a metal rod that spans the entire axle and effectively joins each side of the suspension together. When the suspension at one wheel moves up and down, the anti-sway bar transfers movement to the other wheel. This creates a more level ride and reduces vehicle sway.

If you don't have a stabilizer bar, you tend to have a lot of trouble with body roll in a turn. If you have too much stabilizer bar, you tend to lose independence between the suspension members on both sides of the car. When one wheel hits a bump, the stabilizer bar transmits the bump to the other side of the car as well, which is not what you want. The ideal is to find a setting that reduces body roll but does not hurt the independence of the tires.


Upper and lower braces help to stiffen up the front end of the chassis. Believe it or not a car is not as solid as you think. Through corners, acceleration and braking chassis flex and twist due to forces applied on the car at these times. In a race car a chassis will be as stiff as possible to help it corner well, in a road car there is less support. The reason for this is that its expensive to fully stiffen a chassis and in an average road car the extra rigidity is not needed as the forces applied are not as great as they are in a race car.

Upper and lower braces are designed to stiffen the chassis and basically work as a bar, tying together two points to hold them together to make sure they donít move. The upper strut brace attaches to the top mounts on the front suspension mounts (can be seen when opening the bonnet). The lower brace attaches to the bottom of the suspension assembly on the underneath of the car. Fitting these will stiffen up the front end of the car, which helps to keep the car rigid through corners. This will be noticeable as cornering will become more stable and more predictable, which in turn gives the driver more confidence. They also help to give the car better turn-in through corners too. The upper strut brace looks great too under the bonnet.

Both the upper and lower braces can be fitted separately or together, but work better together.


As with most cars, Evos respond extremely well to aggressive alignments. Getting a proper alignment is arguably the cheapest mod to your car that you can do that will net noticeable, real-world benefits in your car's handling or your lap times. Your Evo offers OEM adjustments for toe front and rear as well as camber adjustment (albeit only a simplistic +/- one degree adjustment in the front via an eccentric strut fixing bolt).

To minimize understeer (yes, your stock Evo WILL understeer, especially at lower speeds), set your rear toe to zero or up to 1/8" total toe out. Front toe settings can also be ideal between zero to 1/8" total toe out.

Toe in tends to make a car more stable, but reduces its ability to rotate and slows initial turn-in response. Toe out helps a car to turn aggressively and can make it more nimble, but can lead to unwanted oversteer. NOTE: no matter what your alignment settings are, your Evo can still understeer AND oversteer. Your inputs to the steering, brakes and throttle determine handling response as much as any vehicle factor.

Once you add coilovers to your Evo, you will likely have adjustable camber plates that allow you to increase the negative camber of your front tires. Increasing negative camber up front will helps the front tires to be planted more squarely to the road surface under cornering loads, which increases grip and reduces the car's inherent understeer.

"Ideal" camber settings for handling are somewhere between 2 and 3.5 degrees negative for the front, and about 1.2 to 1.5 degrees negative in the rear. However, read on to get the "no free lunch" disclaimer about setting your alignment outside of what Mitsubishi intended.

Ride height:

For many of us, a lower Evo is a better-looking Evo. Admittedly, it looks like a monster truck from the factory. However, when you lower an Evo based purely on your desired aesthetics, you can actually make it handle WORSE.

This is because when you lower the Evo more than about 1" from its stock ride height, you risk lowering your car's roll center below the ground under compression, which will actually REDUCE grip and induce understeer. Also, if your front suspension bottoms out on the bump stops under load, your spring rate will go to infinity (i.e., no spring at all), and then the result is again terminal understeer. Basically, there's much more to optimizing handling than just minimizing your center of gravity by lowering the car.

A very simplified way to determine if your Evo is too low is by checking the orientation of your lower control arms. If they are angled "downhill" towards the centerline of the car - i.e., the pivot point/fixing bolt at the wheels is noticeably HIGHER than at the other end - your car is probably too low.

Also, the higher your spring rate, the lower you can go with your ride height, because your suspension won't compress as much under load.

For more detailed information on optimizing your car for ideal handling, taking roll center, ride height, rake, alignment, spring rate and ride height into consideration, check out this thread:

Spring Rate:

Evos come with fairly soft spring rates from the factory (180#/in. F, 225#/in. R). While the Evo is of course an amazingly competent car as is, there is still a lot of room for improvement, and a lot of this improvement can be achieved through higher spring rates.

Higher spring rates reduce left-to-right body roll, as well as offering more controlled front-to-rear weight transfer (something that anti-sway bars CANNOT do), but more importantly, they allow for higher overall grip, assuming that your tires are sticky enough to achieve these increased cornering limits.

The spring rate that is appropriate for your Evo depends on your intended purpose (autox, track days/road racing, etc) and what type and size of tires you are using. Generally speaking, the stickier the tire, the more benefit to higher spring rates, assuming your dampers are up to the task of controlling that spring.

Most people who want a neutral-handling Evo will run 150-200# stiffer springs in the rear; however, if you are using aftermarket sway bars, this changes the F/R spring rate equation significantly.

Also, softer spring rates are appropriate for rougher or more slippery surfaces (e.g., Heartland Park's sandy asphalt vs. Forbes Field's weathered concrete).

The main downside to increasing the spring rates under your Evo is a harsher ride. Your ride height, damper settings (if adjustable), and type/quality of damper will also affect this to some extent. What is "still acceptable" for street driving is highly subjective - some people think that 600#F/800#R is fine for a daily driver, while others would think they're crazy.

Keep in mind that someone who enjoys smooth roads in Florida or California will think that his setup is still "totally streetable," but he'd probably change his mind real quick if he lived in Detroit or Chicago.

Final Thoughts:

There is no free lunch when it comes to alignment or suspension mods. A change that is better for one thing is typically worse for another. When you start getting serious about improving your Evo for handling - lowering ride height, increasing spring rate, altering your alignment settings, replacing rubber bushings with urethane versions or spherical bearings, using "pillow mounts" with spherical bearings as opposed to the OEM rubber bushings - you will typically degrade ride quality... increasing noise/vibration/harshness (what automotive engineers call NVH), tire wear and how sensitive the car is to unsmooth/grooved pavement.

Having toe-in, toe-out or negative camber will all contribute to an advanced rate of tire wear. This is because instead of the tire rolling perfectly straight forward and with its tread square to the pavement surface, you're actually "dragging" the tire across the surface slightly as your car drives forward.

Some people think that negative camber is the main factor the causes fast inner edge tire wear, but in actuality it is a result of a toe-in or toe-out setting combined with negative camber. Bottom line: if you lower/raise your Evo with aftermarket suspension parts, GET IT ALIGNED.

There is no "optimal" alignment setting for both handling and minimal tire wear... it's a compromise that you will have to decide upon.

Also, having a lot of negative camber up front in an attempt to increase cornering grip will reduce the contact patch of the tire for straight-line braking. There is definitely such a thing as too much negative camber, even if you only care about performance, but what that exact figure is depends largely on the type of tires you are running, your ride height, your spring rates, etc etc.

General Clutch Information:

Courtesy of RoadSpike

For the installl go here:

or here:

If you want opinions on what clutch is the "best" you better just search around. Everyone has an opinion why twin disk A is better than 6 puck B..

Clutch Types:

Single organic:
Its a disk almost always sprung with an organic/carbon friction material in it usually with some kind of binding fibers pressed into it. Most people call these "street" clutches but it really just means easy to drive and low torque holding.

Racing Clutches (with pucks):
What is a puck? Well it looks like a brake pad stuck to a metal plate mostly made with something like a ceramic composite. It grabs HARD and does not have a real friendly slip pressure like an organic clutch. To compensate for this revving the engine a little more before slipping engagement seems to help with the take off. These kind of clutches hold lots of power and can come in sprung or unsprung.

So what do you do when you run out of surface area for friction on a clutch? Well you make more surface area by stacking clutches on top of themselves. Thus the really crude idea behind a multi disk clutch is that simple.

Means simply you have a set of big springs connecting the friction plate to the shaft. Its supposed to prevent the shaft splines from being damaged on hard launches but honestly all its seemed to do for me is create clutch chatter on take off..

In evo aftermarket clutches it seems to prevent take off chatter having a solid clutch. Of course you run the risk of spline damage instead.

Pressure Plates:
Pedal pressure bothering you? Perhaps your clutch manufacturer thought instead of making the friction material better they'd just slap another 1000lbs of force on the clutch instead. Unless you like light switch like feel try to avoid extreme pressure plates and go for something more sensible.

Lighter flywheel means you will probably have to gas it on take off or risk a stall. Rev matching is somewhat easier since the engine will spin more freely.

Braided line:
Did I feel the difference? Well... no but it looks cool!

flywheel/pressure plate/clutch disc - overview and information

Transmission Specific:

Courtesy of EGbeater

Transfer Case:

The transfer case on the Evo 8/9 is under a lot of stress. It gets very hot because the downpipe runs right next to it. This is especially true if you run your car hard regularly at track days or even autocross events.

There are more than one opinion on what the "best" fluid to use is, but the OEM Diaqueen fluid is a good choice for a daily driver. Not a bad idea to change the transfer case fluid every other oil change, despite this being a shorter interval than what the factory recommends.

IMPORTANT: Getting the right amount (i.e., enough) fluid back in can be tricky, especially on Evos with ACD (Active Center Diff). Here are two how-tos on refilling the T-case:

Just like with engine oil, it doesn't really matter how awesome the fluid is, or how clean or dirty it is, if you are 50% low on the AMOUNT of the oil, so properly refilling your transfer case is of utmost importance.

Keep in mind that the oil in the transfer case doesn't just provide lubrication; it also plays an essential role in controlling heat. When the transfer case is low on fluid, it also gets much hotter than it's supposed to, which further compounds the abuse on an already highly-stressed component. The transfer case is expensive to rebuild or replace, plus it's not fun to remove/reinstall, so you need to prioritize taking good care of it.

Rear Differential:

The Evo comes with an OEM rear LSD (limited slip differential). As compared to an open differential, it does a better job of putting down power when the car is cornering and the inside tire has less weight on it. However, the OEM diff will quickly wear out with use, especially if you've upped the power output of your Evo substantially.

If you're using your Evo for autocross or track driving, you can make a substantial improvement in the car's ability to power out of corners (and therefore not understeer as badly) by having your rear differential rebuild or upgraded. If you're mostly drag racing, the rear diff doesn't have as hard of a job, since the car squats and puts an almost-equal amount of weight on both rear tires, but you might still see improvements with a rear diff upgrade. You can also replace the OEM differential with an aftermarket unit, but this is a more expensive option.

Two place to have your rear diff rebuilt:

Once you have your rear diff upgraded, you can further finetune its performance with the fluid you use in it. Believe it or not, this makes a HUGE difference in the lockup characteristics of the diff. Using Redline 80w-140 NS (as Jon @ TRE recommends for drag junkies, trackday whoring or autocross warrior use) will make a night and day difference in how much the rear diff locks as compared to using OEM Diaqueen fluid. The fluid also directly affects how much noise the diff will make. More locking = more noise. Sorry, can't have your cake and eat it too.

There is a ton of useful (and thought-provoking) information about Evo drivetrains at the two websites below:

Obviously, some of what is stated here are opinions, not irrefutable fact. However, I think it's fair to say since these statements and opinions are from two very experienced drivetrain shops, they are at least informed opinions with direct, real-world experience behind them. So to me, that's worth a lot. But I'm sure there are plenty of people who would disagree with some of their statements or recommendations.

Last edited by chaotichoax; May 11, 2011 at 03:31 PM.
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Old Mar 6, 2008, 01:12 AM
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Thanks to RoadSpike for a solid beyond bolt on/suspension contributions.

Thanks to Jameson_IXMR for suggestions of boost gauge, o2 housing, and shifter bushing ideas.

Thanks to EGbeater for stock frame turbos and suspension contributions

Last edited by chaotichoax; Sep 22, 2009 at 01:17 PM.
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Old Mar 6, 2008, 03:04 AM
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Nicely done. Very informative. *sticky*
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Old Mar 6, 2008, 03:43 AM
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bump for waiting for this a long time
what about me, Im 100% stock will a flash help me gain some hp, without any other go fast mods?

Last edited by DRAGHICI; Mar 6, 2008 at 03:46 AM.
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Old Mar 6, 2008, 04:06 AM
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This is an outstanding addition. I have exactly all those basic bolt-on modifications. I had to do a lot of research to find out what exactly to buy and if this was here it would have made decisions a lot easier. Great job chaotic.
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Old Mar 6, 2008, 04:14 AM
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+1 on sticky! Make it easy to find since most people post a thread before searching.
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Old Mar 6, 2008, 05:32 AM
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Originally Posted by DRAGHICI View Post
bump for waiting for this a long time
what about me, Im 100% stock will a flash help me gain some hp, without any other go fast mods?
Yes, along with better fuel economy

I vote this thread be emailed to every new member.

Last edited by Redline-Z; Mar 6, 2008 at 05:34 AM.
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Old Mar 6, 2008, 05:56 AM
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awesome write-up. I second that this should be e-mailed to every new member. hell i even learned some stuff after reading through it.

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Old Mar 6, 2008, 06:18 AM
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Man that would be a great sticky..
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Old Mar 6, 2008, 06:26 AM
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YGPM. Great thread.
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Old Mar 6, 2008, 06:29 AM
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Old Mar 6, 2008, 06:35 AM
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Great info...Too bad there will be n00bs out there that will overlook this thread.
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Old Mar 6, 2008, 06:39 AM
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Great job!
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Old Mar 6, 2008, 06:41 AM
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very nice. Perhaps to go along with the tuning section, put in wbo2?
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