Just an idea that came to my mind! A lot of ppl are saying custom dual exhaust would loose a lot of back pressure hence loosing a lot of low end torque. I was thinking how about a dual exhaust setup with stock mufflers on both end? that would still provide back pressure (definitely less than stock with single muffler) and also minimize the noise, while giving some gains?
just an idea...

 

those stock mufflers weigh a ton! imagine having 2!

 

again, why duals?

 

thought it would increase hp without much noise (with stock mufflers)? since reducing restriction with single outlet will always increase noise

 

x2... they do look cool tho...

 

yea they do :P

i dont know i thought it could reduce restriction while keeping the exhaust muffled

yea thats another problem....

 

you should look around for some mufflers that might maintain a little backpressure and just go with those, i think flomaster makes muff's that maintain backpressure but less restrictive!

 

why not one muffler that has two outlets? that would look cool

 

^^^ or that!

 

i can just picture two stainless polished exhaust tips (smaller of course) replaced with the orginal muffler..i think that would looks sick, and i think ive seen it done before..

 

yea i've seen that, or put the muffler further back and run the other pipe to the opposite side of the car.

 

that could work two..what i was talkging about would be similar to the cavy z24 exhaust..just alot more polished and coolerl ol

 

yea i heard about flowmaster, but i want to find a setup that would retain the stock exhaust note while giving performance gain ...ideally

 

i say do it, you might not get to much of an increase in power but its quiet and looks good

 

I have dual outlets, with a custom 2.5" exhaust, and i have not felt this backpressure drop people keep talking about. It runs just as good as with the single.

 

Single passenger side side pipe that would look bad ass. Not to mention burn you passangers ankles when they get out.

 

burnt ankles suck ha haha anyways ... duals are great but flowmaster is gonna be too much exhaust for a small engine. just find a nice dynomax or something single in dual out

 

lol Please, I had a 2.25" Flow master 40 seriese on an 88 skyhawk with that 2.0 N.A. With mods it was putting down like 130 mabie 140 hp and it ran just fine.

Just caught you were refering to a dual setup there are a great many single in Dual out options from flowmaster im shure there is a 2.5 in 2 out or similar.

 

the goal of my idea is to have a setup that's almost stock noise with gains....

i'm gonna research more before i start on this...

 

To begin back pressure is the enemy. Do everything in your power to kill it, the trick is not to go overboard. Duals on a street 4 cylinder are very necessary unless your going for a specific look. Corsa makes the single 3 inch dp and cat back that is used on the Time Attack Cobalt and the other professional road race cobalts. So that should tell you 3 inch is overkill for the street unless you've got something serious going on. Also the further away from the engine a restriction is the less affect its going to have on engine output. So you could in theory have tubular header with a 2.5" high flow dp matched to a 2.5" cat back with an adapter necking the pipe down to the factory muffler. I wouldn't think it would sound much different and the only restriction would be the factory muffler.

 

backpresure is not the enemy. you want some. elimintating some BP is good but little to none will leave you with no low end power.

 

Cutting back pressure does not cut the low end power, free flowing exhaust will always show gains. The shape of the torque curve is baced on a huge number of things. The most basic variables we can change on our cobalts however is the length and diameter of the piping used for the exhaust. Longer length smaller diameter piping will generate more low end torque at the cost of high rpm hp. Shorter larger diameter pipe will as you said kill the low end tq but produce better hp because of its superior high rpm flow. Like I said you just can't go too far, thats the trick.

 

yahhh, on cavs and sunfires lol

 

You could always do what some people have done...(ive seen it in person)

Buy the tip, attach it to a piece of exhaust tube...and make it appear that you have dual exhaust, when in all reality...you dont. (make sure you atleast spray paint the other exhaust inside to look like its being used).


Or, you could do with what im going to do....(Than again, i dont have a muffler)...make a Y. and split it off. Granted 1 side is going to be louder, since the original exhaust location will have less piping, as the secondary will have to split across.

But they will be functional.

 

backpressure does make a difference. I had a larger DP with my catback and i feel like i have MORE power now that i put my stock DP back on.