Friend of mine went from a dual 2" (86 camaro) to a single 3.5" with a 3" Y-pipe and picked up 6/10th's. No joke.
I think you won't see an ET difference with 3" to the mufflers & 3" tailpipes to 2.5" tailpipes, due to the mufflers.
Muffs are where the biggest loss is at.... and the only
reason I am saying anything is due to your statement
"DUE TO MUFFLERS"... I got way too many years testing them
and I designed the F-body police car exhaust with dual
fronts to dual muffs and a rear Y pipe... where do you
think your buddy got the idea from... it was done so the
cop cars could run a bigger fuel tank but we didnt have
the room for dual tail pipes... by the way that was
in 76
