I'm installing a JDM DC Sport header and a 2.5" Carsound cat. From the cat back will remain stock ITR exhaust. What flanges will be needed? Should I use the OEM flange? What about the out end of the cat, will I need to order a flange for that side? Also the bracket that is needed for the OEM JDM header, is it needed for the DC Sport?

 

For the stock exhaust, you need a 3 bolt flange. You can find these on kteller.com. Find the appropriate size for the outlet size of the cat to match up against the stock b pipe. Don't forget the gasket.

As an aside, someone in the classified has a 2.5" mugen TL exhaust set up for 500 clams. Wish I would of seen this before getting a T1R bpipe...