BOOSTU

So i bought a set of OBX 1 7/8 headers and behind the header it turns into 2 1/2 inch should I return and buy 3"? Will it make that big of difference in HP? From what ive found its only like 5 HP... Im running Z06 Bi-mode over the axle mufflers also.

GS057

Your Z06 mufflers should be 3 inch. Might want to exchange it for the 3" version.

BOOSTU

Im just trying to figure out if there is a big power difference. The Bi-mode goes to 2 1/2 inch right before the muffler and all the way through.. Im just looking at it like, I have 2 1/2 right now so it would be that all the way through. Or if I get 3" Ill be in the same situation because of the 2 1/2 restricting it at the muffler..

JakeC6Racing

2 1/2 should be plenty and won't restrict anything unless you have an ls7 or you're boosted

HOXXOH

You have close to the best power with your current setup. It'd be better with 1 3/4" primaries though. Until you have significant internal mods or go FI, the 3" all the way to the mufflers is not only not needed, but will reduce the velocity and therefore the power.

The best power for bolton LS3's reduces the diameter to 2 1/2" somewhere within the X-pipe length.

CMY SIX

EVERYBODY brings up the fact that the Z06 pipe necks down gently right before it goes into the muffler what size it is, is not really known. WHat I'd like to point out about the Z06 set up is the Diameter if the exhaust pipes/tips IS greater then the stock set up thus providing better flow. IMHO you'd have been better off saving the $ on headers and just put the Z06 maniflods on, when you took off your stock cast iron manifolds you saw they where just like shorty headers.

HOXXOH

It's actually 2.5" diameter and it's not gently. It happens in less than the last inch.