Differing size pipes make much difference?

1972DusterPaul said

Since you didn't mention anything about your motor, I looked up a couple of your posts.

2-1/4" or 2-1/2" tailpipes won't matter much in your case for performance...the smaller tailpipes might be a bit quieter.

Smaller tailpipes used to be common to make the exhaust installation easier.

I can't find it, but a while back I read a good exhaust article on a Pontiac that ran 12.68 with 3" exhaust all the way and when switching out the tailpipes to 2-1/4" his quarter mile time changed to something like 12.71. Exhaust gases cool significantly after the muffler so larger pipes are overkill.

If you wanted to keep the exhaust tips you already bought then personally I would go with 2-1/2" pipes to the mufflers...also with an X-pipe...then 2-1/4" tailpipes out the back.

Otherwise I would run 2-1/2" pipes all the way front to back.

Paul

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there may be more variables to that pontiac, i agree to some of that thinking but i can also se how that would work on a chamberd or 3pass muffler but dont think it would work as good on a car with absorbation mufflers.
also depending on the whole car those 3" exhaust pipes may be overkill in the first place.
back on topic i like to build ehxuast the same size as the collectors all the way back but dont think a slight reduction at the tips would make much diference but thats just my thoughts since it gives abit more room for future development to have the bigger pipes already there.
alot of these things about smaller tailpipes because they are easier to bend and install is something i bet comes from lazy mufflershops that may be lacking the knowhow on how to do it once and do it right. LOTS of pontiacs had bigger tail/overtheaxlepipes than exhaustpipes already from the factory,and i think that may be for a good reason,those bigbends create restriction and by going up one tubesize some of that loss could probably be gained back.