I want to have a daily driver car, that would not go any higher than 18 psi. would a 3" exhaust suit my flow needs such as a hks carbon/ti. or would something like the gt spec apex exhaust with a 3.7 ish be better. this of course will go along with a DP and MP. I don't care about noise either.

 

is this that stupid of a question?

 

Exhaust systems over 3" ID are few and far between and I don't believe you'll require anything larger, just make sure you don't have any restrictions (like a 2 1/2" flange where the midpipe and cat-back meet). My T78 runs just fine through a 3" exhaust (3" DP, 3" midpipe, 3" catback). The HKS is a nice piece though...

 

so would you get any substancial horse power gain if you had a 3" dp, 3" mp to a 3.5 cat back? and the if the piping is a larger diameter does that give you a deeper exhaust tone

 

well the bigger the exhaust all the way around the more exhaust that is going to be relised and faster turbo spooling. SO in my eyes i would go with biggest for the reason of exhaust flow rate. Marc

 

and another thing if your only gonna go to redline once and a while you probly wont make enough exhaust flow to benifit from the bigger exhaust. ONly high rmps youll be pushing enough exhaust gas.

 

thanks man, I don't want to redline often. I just want a to4e, something to come alive around 13 psi , so I guess I'll stick with an exhaust with a 3" piping.