Need help, looking at getting Vishnu X-flash and cam gears. I don't think I want the exhaust for Stage 1, because of noise, cost, and my perception that most of the gains are not from exhaust upgrade.

1. Does doing these mods without exhaust change sound reasonable?

2. What is the site of most restriction in exhaust (could I get decent gains with just a DP without alot of noise)?

Any help much appreciated - gotta make a decision soon

 

If your exhaust is stock, the most restriction is located at the tail where the muffler attaches the midpipe. Straight sans bends is the only way to make the most power. A cat back ex. will help here, DP will assist the previous. Installing a dp to a stock exhaust is a waste of time & $$.

 

Where did that perception come from? I think most vendors/tuners agree a better free flowing exhaust will show gains. Cost? Won't cams and installation be the same price for a catback?

 

Might want to look into the Buschur 2.5" down pipe and muffler delete pipe. Word is that the sound level is close to stock while freeing up some ponies (10-15whp or so?). If you want to spend some real money, Works offers the same thing that is "prettier" for about 3 times the cost...

 

First off, exhaust changes will give you very good gains. A turbo-back exhaust will net you roughly 25 hp. No, getting a XEDE and cam gears will not affect noise level, and the most restrictive parts of the exhaust is the catalytic converter and the muffler. I would change out your exhaust system, well worth the money.

 

Just find a used exhaust

 

Whatup,

The exhaust is definitely worth noticeable gains.

I replaced my AB muffler with a Bushur AB and it made a noticeable gain, mostly in the upper rpm ranges. I added a 3" Helix DP, and it made more of a SOTP difference than I expected. It also made the exhaust deeper and slightly louder. I have a 3" RT highflow cat on the way, so it should help somewhat as well. I'll have to see whether I get a CEL or not.

I am also concerned with noise, which is why I started with just the muffler, but I got a ticket for altered exhaust (with just the AB) anyway, heh. I did beat the charge at a magistrate hearing though. So, I decided to upgrade the other restrictions in the system. I don't think the midpipe is going to make that much of a diff with the upgraded dp, cat, and muffler, but I may get a 3" cat back at a later date, perhaps one with a silencer or one that isn't too loud.

Anyway, I think at least a mild exhaust would really synergize with other mods (cams and cam gears), otherwise you probably don't reach the full potential.

Take care,

FB

 

Hm, just curious, what did you tell the judge?

 

In my 96 maxima, this is the case, as you get 15hp from y-pipe replacement, but <10hp more for the entire cat and catback - I do realize that NA cars are different.

Can anyone post link for pre and post dyno for axle-back or catback or turboback exhaust? I was thinking turbo back would only yield about 15hp, as every EVO generation lists "improvent in exhaust flow" over previous gen.

 

Wrong my friend. A turbo-back will get you more than 15 hp. A cat-back might get you that much. Keep in mind that this is power to the wheels. NA cars need some back pressure thats why hp gains on your maxima's exhaust wasn't all that great, but free up the air on a turbo and you just unleashed a monster!

 

The most restrictive part of the stock evo exhaust is the muffler. it is not straight through and has a spring loaded gate which is quite restrictive. You can get any number of good axle back exhausts that dont make more noise than stock. As far as getting the cam gears etc, I'd say there's a reason why the first step in every major tuner's "staged" upgrades for the Evo includes an exhaust upgrade.

 

The cat is the most restrictive piece. The stock muffler is easy to mod by proping open the flap but you are still left with a nasty right angle turn. An upgraded down pipe will allow the turbo to spool better (quicker and stronger) but the rest of the system needs to be modded as well. A good full system is expensive but if you go with a better dp a decent muf shop can easily duplicate the rest of the plumbing. You will need a hiflow cat and some sort of straight through rear muf to get the full benifits from the more efficient cat and DP. I would not speculate on a hp number but it should be very apparent that you are making more power.

 

so what would be the best setup for making the most power and having it as quiet as stock?

im used to loud V8's and rear tire noise. a huge part of the fun of an Evo is the sleeper status while on the gas (no tire noise or exhaust noise).

my last ticket was for "excessive acceleration" in my Camaro. the cop told me he heard my exhaust, turned to look, and saw me "taking off a little too fast".

would a DP and axle-back (quietest muffler possible) provide a noticeable difference in power or noise? if so, how would the difference compare to a completely open 3" full exhaust?

if my plan is to have cams, IC piping, maybe a better FMIC, how much would just the DP and the axle back restrict compared to the aforementioned 3" exhaust?

has anyone seen the inside of the stock resonators? if so, how baffled is the internal path?

what im considering is having a bigger DP, high-flow cat, and custom 3" exhaust pipe with as many high-flow resonators as possible. i would get the dynomax ones that have the same internal diameter as a regular pipe and no baffles restricting the flow (if the stock ones are heavily baffled, they likely make a huge sound differnce, which would likely make this whole idea moot).

so i figure i could fit at least two of the dynomax resonators under the car, replacing the stock ones, and then run something like a dynomax super turbo muffler. does anyone think that this setup would be anywhere near the stock db level at full boost?

thanks in advance

 

You would be fine with one resinator... MagnaFlow seems to be the quietest set up for making your own exhaust right now... they also have good clean resinators as you described. You can just get a longer one installed. You'd probably be happy with the Buschur exhaust with the MagnaFlow option... if not, you could then always have the resinator installed later.

 

Zeus, thanks for the response. You really think it would be as quiet as stock with just one?

Come to think of it, if I could make it quieter than stock, that would be cool too. The stock exhaust sound is closer to a 70's full size van on the freeway, so I could easily live without that.

Does anyone know where I can find some good underbody pics of an Evo 8?

TIA