I'm looking for quietest first before flow. Straight flow through design will not quiet things down to as much as I would like unless I run something huge that wont fit anyways.

I'll keep this thread updated. And pm you once I get done with this project. But it will take a little time...

 

All this summer on my 35r setup I ran a 3" downpipe w/cutout to a stock catback.
On pump gas I would run with the cutout closed.
It ran 11.4@124-125mph at 20-21psi
On race gas I would open the cutout and it went
10.7@135mph at 33psi
With the cutout closed the car sounded almost stock unless I got onto boost and the wastegate opened.

On my new setup I will be going a similar route with the stock catback.
good luck
pm me if you need any more info

 

That external wastegate could of helped out a lot...

 

that could have helped, but I was still very happy trapping 125 on pump with a stock cat back. Its unbelievable how quiet it is going down the track.
I will see if I can find the vid on youtube

 

running a highflow cat will reduce sound but not rob as much power as running a stock exhaust

 

Thank you for responding!!!

Damn it I almost didnt want to hear this because I had my heart set 100% on getting a chambered muffler but now I am having doubts whether to go stock catback route or 3" chambered muffler route. Its like 65% chambered route vs 35% stocker.

 

Please post the link to your video clip here if you find it.

Also can you describe the actual loudness in the car? Is it very similar to stock sound level? Many people keep saying that their car is almost as quiet as stock but in the end they just have low standards when it comes to exhaust dynamics and its actually not that quiet.

 

like others have said, and you can obviously tell, the chambered 3" will def net you better power.

As for the evoM member goin 117 on the stock cat back, that was Dan aka fimotorsports, his evo IX went 11.4@117 with minimal bolt ons

 

Well your right the 3" will flow better but will it be louder than I want it to be? Thats what concerncs me.

I think there is a market out where people want quiet as possible and squeezing out every inch of WHP is not as important as silence. Why wont the vendors listen?!

 

I didnt look thru the whole thread but I think this is the post you guys are talking about



https://www.evolutionm.net/forums/sh...d.php?t=235538

 

It was mentioned already, but thanks for trying to help.

 

The vendors have listened. Unfortunately it isn't cost effective for them. The only options are Works stealth system, or the Fujitsubo (quiet unit). Anything else with a test pipe and 3" downpipe will be loud as b@lls. The way the big boys get around this issue is through the use of butterfly valves. BMW, Audi, GM, they've all been using these for years and the aftermarket manufacturers for those vehicles offer the butterfly valve option on their exhaust systems to accomodate those vehicle owners. I was almost at the point where I was just going to accept the fact that in order to have power, the Evo was just going to have to be loud. But screw that, the noise is just too much. I think I'll be experimenting with ideas I have over the winter while the car is parked.

 

I think you are over analyzing.

The quitest will be stock cat back followed by fujitsubo or hks silent hi power. unless you plan on upgrading the turbo, all 3 solutions will probably be within 10-15 hp of each. If I was to do it all over again for my car, I might have had installed a resonated 3" test pipe instead of straight through test pipe. even now, with cams, dp, test pipe and hks silent the car is ok to drive for me. if you want quiter, you will have to forgoe HP. my car currently runs circa 400hp (or around 110whp over stock baseline)

BTW, mine was a compremise - I wanted to have the quitest system without changing bungs etc and still reach the HP where I am.

 

I was in the same boat as you. I just didn't want a loud exhaust anymore, and my 3" turbo back had two resonators, a high-flow cat, and a magnaflow muffler.

I bought a QTP downpipe, a DMH e-cutout and now use that mated to a stock cat and cat-back. The car is fun to drive again...stock sound levels again. If I ever want max performance, in 2 seconds the cutout is open. Granted it is loud, but that's only when you want it that way, for track use or whatever.

 

Like all of you i was in the same boat, Got tired of the LOUD *** exhaust..

So this is what i did, 3"dp, MR resonated TP, Stock Midpipe, Works axleback exhaust, I freaking love it...