what kind of gains should be expected with a full 3'' exhaust system compared to a 2.5''?

 

Depends on how much boost we talking about, if turbo, a good amount, if S/C above 10psi, good amount as well. As far as how much? Well I recall MardisGrasMax picking up almost 60whp on the 3" exhaust including the Ypipe.

Dixit