I've been wondering what size pipes are ideal on a 455. If you stick headers on it, and then collectors into 3 inch, that seems to be some kind of standard. I've got 2 / 2 1/4 now, would a change to the set up mentioned above make any difference, or do you need to do it the whole way with porting, and intake too, to make any difference? The car is a daily driver, with the only performace upgrade being an HEI, which is being re-curved as soon as I find all the right settings.
For a daily driver 455, 1-7/8" headers with 2.5" tailpipes is fantastic. If you are going a bit more hi-po, some people have 3" tailpipes, but those are too big for a daily driver IMO. 2-1/4" should be fine as well, if you rev above 5300 they might hold you back slightly, but this is not a racecar. -Bob Cunningham
I agree with Bob. Unless you have a bit of head work done, a 3in. exhaust system will not help a stock motor. 2 1/2 in is perfect though. John.
