Im swapping a 33-350 Hp 355 in an 86 iroc and looking for some tips on an exhaust set-up that will allow me to "grow" over time and not have to replace the exhaust. I want something that can eventually handle 450-500 hp. Will a 3'" cat back support this? Currently im looking at some eldebrock 13/4 headers and a dynomax 3 " catback(i like the dynomax cuase i want it to be quiet at idle but be louder at WOT)...would this support my eventual goals of 450-500 hp or should i look towards something else?Mufflex? Random Technology? MAC?Looking to keep costs at a minimum but if i have to spend the money i will(i dont want to have to change the exhaust twice!)-Thanks

PS-no duals its a daily driver and i need ground clearance

 

I dont know for sure, but I have heard that around 350 3" starts to become a restriction. Of course you can make more power than that with a 3" but that doesnt mean that you will get all you can out of it. I plan on duals but since you dont want duals, I would see if there are any local shops that can make you a custom exhaust that is bigger than 3 if you decide to go that route, because although it appears to be nice the mufflex is friggen expensive. Also, I dont know for sure, but I read on here that the dynomax catback was actually only 2.75 and not really 3 but they may make more than one. Maybe someone else might be able to help you out more but I thought I would give it a shot.

Ben

 

I want to say 375-400 hp, someone posted a chart a while back.

 

I've seen cars run high 10's with single 3" exhaust but I'd have to say around 400HP it'll start to become a little restrictive. You could look into some of Mufflex's systems. They make 3.5" catbacks and 4".

I personally think you'll be alright for quite awhile with 3"

 

Bet the ones running 10s with single 3 were not naturally aspirated.

Ben

 

You are correct. Mid 11's on motor.

 

I think that 3" becomes a restriction over 300-350 horsepower. I dont think it becomes a problem, however, until upwards of 400 horsepower. You can do anything you want, but i have a feeling if you were running single 3" on a 425 horsepower motor and switched to dual 2.5" or 3" you would pick up a few tenths in the 1/4 mile.

 

https://www.thirdgen.org/techbb2/sho...hreadid=103711


This car goes low 11's with the exhaust closed. And a bit faster with it open. 3 inch cat back. Perfect example of what you would pick up. I would say high 10s aren't far off for him.

 

https://www.thirdgen.org/techbb2/sho...hreadid=140973

It all depends on what's in the exhaust to restrict it, like the mufflers.

Go to www.Dynomax.com and look at there Powertech system. Then look for the 3" muffler that will suit your needs. Not much easier than that.

Keep in mind that the more flow, the louder the sound.

And don't take this is me trying to say Dynomax is the only way to go (even though I am a little biased ). Any muffler that's made to flow well will fit the bill. After you do that, it all comes down to the type of sound you want.

AJ