You should do a 3" all the way through but many are scared of the 3" pipe on this forum.

 

bottleneck with a 3" DP to a 2.5" Cat for back pressure

 

im not scared of 3" piping...im just trying to retain my corsa exhaust

 

I agree with onyx when he says alot of people seem to be scared of 3". I didnt think I was going to tear into the car so fast with performance mods and got my GMPP catback first.Eventually I may upgrade to a bigger catback but I LOVE the tone of the gmpp exhaust and the car seems to be performing great!

 

i aint scarred either, i am getting hahns exhaust kit.. 2.75 dp, and 3.0 cat.. but then again i am getting a turbo down the road, but the catback will be on for awhile.. 07 ss/sc if you want hahns 3.0 give them a call or pm, there price is outstanding.. and from what i was told, i lose just some bottom end, not much though..

i still love the look of your header and dp tho.. amazing.. ::easily amused::

 

Videos added in the first post.

 

Anyone building a LSJ for performance and not using a 3" all the way from the Downpipe to the catback is a FOOL