urban_cowboy

With a 289 dual setup, I would say 2.25 unless you are pushing 300hp. If you go with 2.5" with a stock type motor,I think your low rpm performance is going to suffer. If you are pushing 300hp, then step up to 2.5"s.

jcp123

I have a 2" on mine, and I really can't complain with its performance. Mine's a very mild build though. I'd probably go 2.25 - wish I had. Old hot rodder's trick is to neck down the pipes to the next size down after the mufflers to get some extra rap, but obviously it'd be kind of stupid for me to go down to 1.875 or 1.75"