I want to upgrade my drivetrain system and I need your opinions.
First of all I would like to clarify that I have an European 2006 Evo 9.
That means Transfer case comes with ACD (Active Centre Differential), front differential is Helical Limited Slip (drive to front wheels) and AYC (Active Yaw Control) in the rear differential. (I don’t have a lot of knowledge on that, so please correct me if I am wrong)

What is upgraded until now in drivetrain?
OEM 6spd transmission replaced with Septrans, New 5spd Stage 2 Transmission (including 4.11 final drive upgrade), ACD ECU reflushed and in Transfer case some bolts replaced with bigger ones (I don’t know exactly which ones, from M8 to M10).

What I am thinking to upgrade?

Transmission: Replace 5spd Septrans with KAPS 6spd Sequential Transmission.
Transfer Case & Front diff: A complete rebuilt of transfer case including replacement of front differential. I am thinking to send my transfer case to Sep for Stage 3 rebuilt and replace front diff with wavetrac or Quaife LSD. Which is better? Any other option?
Rear differential: I don’t know exactly what I can do with rear differential. Do I have to replace completely my rear diff with EVO 9 RS diff? RS casing is different or stronger than mine? May I replace Rear Diff with OS Giken, Cusco or Kaaz 1.5 way and keep my casing? Which is better?
Driveshaft: Replace driveshaft with Aluminum 2 piece or CF 2 piece Driveshaft? Which is the best solution?
Axle/Hub kit: Evo IX 900 HP Complete Front Axle and Evo IX 1200HP Pro Level Rear Axle/Hub kit from Septrans.
What is the use of the car?
Car is not a drag car, it is a daily drive car and sometimes road racing. That moment is 553Whp and in future will be around 800Whp. I am thinking to do all those upgrades because I want to lunch as much as I want without thinking all drivetrain system. Because is DD I would prefer parts with less noise, as much as possible.
How you can help me?
Answer in all question marks.
Any inputs from people who test any of the above upgrades in their cars will be welcome.
Suggestions with prices are also welcome, that will help in finding best price.

 

strength and silence don't go together, they are opposites. dogbox with straight-cut gears is going to be strongest

you are saying the car is not a drag car but that you want to launch it as much as you want without worrying about it. it should be classified as a drag car if that's the case

 

Transmission: I would stick with the 5 speed. It will be stronger.
Transfer Case & Front diff: A shep Stage 3 is going to be the best for this. Both Diffs are great. may also want to look into a rs diff.
Rear differential:Look in to the TRE 12 Plate Rear Diff

 

Sequential gearbox is not strong?
Any other opinions/options?

 

why wavetrac and not quaife?

 

I wouldn't put wavetrac over or under the quaife, The wavetrac is proven strong but any marketing hype of preload is wiped away and its just a standard torsen. But a torsen in general can only do so much torque transfer since its still limited by the friction area which is the tiny interface of the spools on the wall.

At a certain point, to put the power down thru both wheels a clutch diff is going to out perform just because of friction area. Especially when it comes to putting power down out of corners.

For gear box, sequential just isnt reliable on a street driven car. They have short service intervals and youd be better off with some version of a Dogbox or Faceplated gear set if you wanted to get away from a normal syncro engagement. But TRE can make you a helluva standard 5speed that will hold up to your power, especially if you arent launching it.

For T-case, just send it to TRE and ask for magic. He'll give you as much magic as he can, no one else is going to get you as durable and reliable as him.

Basically, Trans, Tcase, Rear Diff... Send them all to TRE if you're really wanting the best (And you dont even have to pay more for it, just have to wait a little longer..)

On the driveshaft, if you must change it I would avoid most carbon shafts. The glue joint is the weak point and Ive had too many friends have theirs brake. If you dont launch its probably ok but at 800hp you'll occasionally see wheel hop which I would be worried of failure.

For Axles, the DSS axles are beefy and heavy. They also get real tight on the billet upright options if that's in your mod path. I think we clear the rear uprights by hairs on a few customers cars. I personally stick with OEM axles and just source extras for spares. Rebuild and have sitting around.

 

yes and no..

sequental is a dogbox too, usually straight cut... there is no difference apart from the fact that you cant skip gears in a sequential. Sequential lasts longer than H pattern dogbox because with some practice you always have a clean firm shift and cant miss a shift. A pneumatically operated sequential with DWB and proper engine ecu is even nicer on the gearbox. Both the sequential and normal h pattern dogbox NEED fast firm shifts to live longer. Both also need frequent servicing and are not really a good choice for a street driven car.

 

Ahh, I've heard they are at least most cost/mi to maintain at least. So if you need a dog engagement on a street car, the box with modded gears is the way to go.

On the driveshafts, I cant seem to keep the various details of options straight in my head. @ayoustin still has a young fresh mind, what was the good direction to go if you needed to upgrade?

 

I think the maintenance interval on the sequential is because they are generally made by the larger gear box/drivetrain mfg's and come with recommended service intervals. VS a lot of the dog ring gear sets for using an Hpattern shifter in the stock cases are made by a lot more smaller shops and don't come with maintenance rec's.

But Kiki is right, the transmissions are the same, just a different shifter. And because dog bogs need to be shifted fast if you really want them to live, the sequential makes that the easiest to do since you just yank on the lever.

 

You'll hate your life and your wallet will hate you trying to daily drive a dog box or sequential. Just get a beefed up 5 speed and you'll be set.

As for driveshafts on an evo I'd only run the aluminum shaft from Driveshaft Shop.

To date I only recommend one company for carbon shafts and they don't many aftermarket pieces. They use a propietary system to retain the carbon on the yokes. They're the supplier for the OEM GT500 driveshaft and that drivehshaft is a piece of art.

 

also, dogboxes are noisy as hell, and not just because of straight cut gears... The dog engagement is very "loose" so you get helluva racket on accel/decel. Having said all that I am always on a lookout for a cheap dogbox gearset.. LOL There is nothing more cool than that clack-clack-clack sound when you put it in first..