Right now, behind my 350, is dual 2.25 inch exhaust. For my upcoming 454 I'm going to want 3'' exhaust. If I go ahead and put the 3'' exhaust on now, what is the chance that after the headers for my BBC, I will have to cut some pipe off near the header, i.e. it will go back farther than the sbc headers (toward the back of the car). Does this make sense? To clarify it is straight dual pipes, I believe 2.25 (maybe 2.5 but don't think so) to Hooker Aerochambers then 2.25 tails. Thanks.

I'd wait til the big block is in there,then do the 3" exhaust with either an X or H pipe. Personally I am running an H pipe.