I'm planning on going with the Dynomouth exhaust, for those of you that don't know its basically a Dynomax bullet muffler welded into the stock I-pipe, then the stock muffler is eliminated and a Y is fabbed to keep the dual functioning tailpipes. I am a little worried that the stock 2 3/4 I-pipe won't be enough to keep up with my engine (very soon I am going with Lloyd Elliot heads and a cmotorsports recommended cam) and that I would be better off fabbing up a true dual setup or a 4" cat back...anyone have any thoughts on this?

For those of you wanting more info on the Dynomouth, here is Ratio411's site on it:

http://www.cardomain.com/member_page...=215971&page=2

 

I know of a couple of LS1 guys running big cams running the Dynomouth with the stock I-pipe and putting down great #s. Im also have it and love it. Im sure a 3 inch pipe would help out and a true dual would be great but Im not sure how much the stock I-pipe will end up hurting you. Personally when I go with heads and cam Im gonna run duals.

 

The farther away a restriction is from the exhaust port, the less effect it has. That's one reason headers give a better gain than just a catback. So the question is, what do you have before the i-pipe that may be your limiting factor? Are your "SLP shorties" the dual cat headers? And are you running cats?
Also, you don't 'need' a 4" exhaust until you get in the ~600 hp range.

 

they are single cat headers, still have the cat on it (doubt I will remove it, just doesn't seem worth it to me).

What I'm worried about is losing 10-15HP from having a 2 3/4 pipe instead of a 3" or bigger pipe when I put the cam in there...

 

The SLP y-pipe is 2.5". And since you're going a cat, there shouldn't be much difference between running a 2.75" or 3" intermediate pipe, especially if you go with a muffler as free-flowing as a bullet.

 

at what point do you think the 2.75 pipe will become a restriction? Just wondering if I need to do it later...

 

TTT - anyone?