What exhaust "part" plays the biggest factor in noise/tone change?

[Gleason]

Hey, I'm wondering what gives an exhaust its set 'tone'/noise? I know its more than likely a mix of everything, but is there a piece [ down pipe, cat back, muffler, resonator] that has the single biggest effect?

My REASON for asking, is because I want to obviously make more power with my car this spring [ goal of 300 awhp ] but I love the stock exhaust tone/noise and I really don't want to change it. But i do realize 2.25 is pretty small, so i'm wondering if theres a way to increase my exhaust flow but keeping alot of the stock exhaust noise?

I don't know much about exhaust systems per-say, and had a few n00b ideas i thought i'd run by to you guys.

1] Would a stock exhaust with a test pipe removing the cat, on stock muffler, still be a big restriction? how about when compared to going to a 2.5 inch with no cat and a muffler of some sorts?

2] Could I look for a 2.5inch turbo back or catback exhaust, use a test pipe and somehow try adapting my stock muffler to it? [ i really like the stock muffler looks and i want to keep the police and ricers away . sleeper <3 ]

3] I'm not sure whats inside the muffler, is it restrictive? Are there anyways to make it flow better if it is restrictive?


Also, I saw someones sig on the pocketlogger.com forums and it said they had made 242fwhp on a stock exhaust with big16G, so i'm wondering if a test pipe on a stock exhaust will meet my goals. or could i try running no exhaust with a muffler hanging so cops don't notice. Is that extremly loud, or bad?


I am trying to hit my goals with a bigT28, DSMlink, 560cc evo injectors, 160-190lph evo fuel pump, FP17psi WG actuator, and FP1/fp2 cam combo. ].

 

[Dream On]

Just get a 2.5 in exhaust with stock appearing tips, or a cutout. That way, then you have your stock sound, and then open the cut out when you want to. Just a thought.

 

[wret]

The stock exhaust will be restrictive when you start adding power. Removing parts of it will reduce restriction but the parts you keep will still be restrictive. I guess there's no way to word that without having it sound like there should be a "duh" at the end.

Further, you cannot "open up" the stock muffler to make it flow better. I haven't opened one of these up but typically the inlet pipe reaches far into the shell ending near the opposite end in a perforated section. The idea is to bounce the sound around in there until it gets lost but provide a path for the gasses to exit. The higher flowing mufflers have a less restricted path to allow easier exit for the gasses, but although they don't utilize the same physics of motion, a straighter gas path means a straighter sound path. Fortunately for high performance exhaust/muffler manufacturers, the types of people that purchase their products usually don't mind a little more noise. This is unfortunate for car guys that prefer subtlety but there are some mufflers out there that would offer a decent compromise between power and stealth.

 

[Piranha451]

I would have to say the muffler plays the biggest part. I feel this is because when was installing my cat back and had removed the old exhaust, I started the car expecting to hear a loud/raspy note like open headers but it was dead quiet. I attributed that to the cat still being attached. After installing the exhaust it now made 'noise'. Hope that answers your question...

 

[kronus]

Multiple parts of the exhaust achieve the "sound" that one looks for. One "part" is not responsible for changing the sound of your exhaust all-together.

Removing the muffler will give an increase in decibels (loudness), while removing the resonators will give an increase of rasp. Also, removing the cat (where applicable) gives a dramatic increase in flow and sound.

And removing all of your exhaust except for the muffler will be rediculously loud. And cops will definitely notice; maybe not at idle, but any form of throttle, and they'll be on you like white on rice.

-Kevin-

 

[blackGSX2g]

I think the turbo and exhaust diameter has the biggest affect. My car idles/drives louder with a bigger turbo and 3" o2 eliminator than a friend's bone stock 2g with no muffler (rusted off right after the cat).

 

[Iceman90]

1] Would a stock exhaust with a test pipe removing the cat, on stock muffler, still be a big restriction? how about when compared to going to a 2.5 inch with no cat and a muffler of some sorts?

Yes, just replacing the cat with a test pipe is still going to restrict your exhaust alot. I would say you would see very minimal if any gains doing that. Like wret and kronus said, replacing one part of your stock exhuast and leaving everthing else will barely help at all. Your'e better off just replacing everything or atleast getting a cat-back if you want to see some decent gains.

2] Could I look for a 2.5inch turbo back or catback exhaust, use a test pipe and somehow try adapting my stock muffler to it? [ i really like the stock muffler looks and i want to keep the police and ricers away . sleeper <3 ]

The stock muffler on the end of a 2.5inch turbo-back is like putting a cork on it. You would probably see a little more power than just putting on a test pipe, but again most likely very minimal gains. You could however put a dual tip muffler on the piping which looks like the stock muffler, but flows alot better. It also would most likely be quieter than a signal 4" tip type muffler.

3] I'm not sure whats inside the muffler, is it restrictive? Are there anyways to make it flow better if it is restrictive?

I doubt you could make it flow better at all. And if you could it would probably be almost the same as an aftermarket dual tipped one.

On a stock exhaust the one part that will make the most noise difference by replacing it would be the muffler. For aftermarket exhuasts, there are many things that can make the noise level increase/decrease.

-Resonators
-Catalytic Converter
-O2 Housing w/dump tube
-Muffler Choice
-Piping Size 2.5"/3" (I'm not sure there is a big difference in noise level between the two, but definately a difference in the way they sound.)

If I were you and I was concerned about noise, but wanted performance as well, I would consider this. Run a stock or mild exhaust so noise level is kept down, but when I want performance have a cut-out installed after the 02 housing somewhere. You could just flip it open and closed at will. The only drawback is you have two opposite spectrums, either full stealth and no power or no stealth and all power. However, if you would rather not have two extremes to choose from you could always go with something in the middle. Hope this helps, and good luck.

 

[knight007]

What I did on my RS was the pipe that is right after the cat that connects to the pipe that goes over the axle I just take that off when im at the track. Its like 4 bolts and an o2 sensor not that bad really.

 

[leet]

From personal experience: Mufflers will change the overall tone, but a test pipe (along with a larger downpipe, obviously) will give you that high end growl that is oh so sexy.

 

[sYnOnYx]

i would say muffler. my friend with a GSX and T3/T4 car was really loud , but that changed.

Before: 2.5" downpipe , 3" back no cat , apexi 4" outlet muffler = REALLY FRIGGIN LOUD

After :2.5" downpipe , 3" back no cat , Magnaflow muffler 3" outlet (rectangle stock looking type) = good tone and not too loud still made about the same hp only lost about 1-2hp. and WAAAY less cop attention. looks very stock.

companies sell mufflers that are quiet , but yet arent restrictive...and look stock. check out magnaflow and flowmaster......

 

[dsmgrimreaper]

the muffler is what does, the cops here just see that nice shinny new muffler and the wonderful blue lights come on.
www.meganracing.com

 

[leet]

i would say muffler. my friend with a GSX and T3/T4 car was really loud , but that changed.

Before: 2.5" downpipe , 3" back no cat , apexi 4" outlet muffler = REALLY FRIGGIN LOUD

After :2.5" downpipe , 3" back no cat , Magnaflow muffler 3" outlet (rectangle stock looking type) = good tone and not too loud still made about the same hp only lost about 1-2hp. and WAAAY less cop attention. looks very stock.

companies sell mufflers that are quiet , but yet arent restrictive...and look stock. check out magnaflow and flowmaster......

I would agree, Magnaflow mufflers are generally a bit more quiet.

 

[dave99gst]

for DB's i would say muffer & cat is the big factor.
for tone - the resonators

 

[nocturnalspirit]

if you are like me and you'r not into magna flow mufflers get a raceing muffler and put a scilencer in it and it should sound close to stock