Thread: Confised about downpipe flange size

Hi all--

All right, I'm confused about the size of the downpipes, and I haven't found any conclusive answer despite searching, so here goes.

I'm looking on W Body (3 Inch Downpipe), and it says my options are for a 2.5'' ("for stock exhaust systems"), and 3'' flange ("for 3'' catback'').

In both cases, I'm talking about the bolt-in downpipes. I'm out to get rid of the U-bend.

And I'm completely lost - I'm assuming the 3'' is better, but does it simply bolt in like a 2.5''? I've got an otherwise completely stock exhaust system.

You want the flange to match your cat-back, so you can't use a 3in flange as its too big for your stock cat-back.

You need the 2.5" with "for stock exhaust systems". The 3" flange for 3" catback is only for people who have bought a 3" catback.. the part exhaust system that goes from the end of the downpipe back to the mufflers.