Right now I have a 2 1/4" downpipe. I'm not upgrading to a full 3" for cost reasons and because I wanna keep my A/C. Would it be worth upgrading just the bottom portion? Or would the gains be so minimal that it wouldn't be worth it?

Oh, and I'm getting a 3" thermal and a 3" carsound cat. Should I have a flex pipe put in the system somewhere? Like in the downpipe?

 

Well I don' know if Art has anything for the fmax kit but if he does you could get that 2.5" to 3" downpipe that allows you to keep you ac and has a flex section in it.

That would also give you more power....

 

Flex in the DP is a must unless you want to stress the manifold. I would say get flex for sure.

 

I went with a 2.5" DP with flex and 3" cat. I have 2.25" exhaust until I get it re-done in 3".

I got the 2.5" DP because

a. 3" would probably do nothing for my setup
b. it just wouldn't fit

They are right tho, get the flex pipe to reduce the chances of cracking your manifold.