I can't find this anywhere on search. Do i need a 2.5" catback for the dc sports jdm header? I dont' know if my DC sports catback is 2.25 or 2.50. Do they even make a 2.25" catback? I know i need a new cat right? Just tell me what sizes i need from the header on back.

 

I have the JDM 4-1 ITR header to a 3" universal random tech cat (welded by my local muffler shop) then exiting to a 60mm APEX'i N1 exhaust.

Works great

So that's 2.5" to 3" back to 2.25"

 

if you have the right header for your engine your stock cat will bolt right up. you don't have to replace the cat, but if your going to replace it, do it now. after market race cats are $100-$200. the majority of exhaust are 2.25 or 2.5. the biggest is around 3. made by thermal, made for turbo. i haven't heard of anything smaller. especially for performace reasons. all dc, greddy, tanabe, apexi, hks exhaust systems will do just fine with no worries.

 

so a 2.5 collector header/ a 2.5 cat will be compatible with a 2.25 catback exhaust? would that be bad for performance or will the size difference not make a big difference.

 

Personally, besides the header and 2.5" cat (leave the 3" for FI) i would just go to a local reputable exhaust shop that does mandrel-bent piping and piece together my own 2.5" exhaust setup. Then just carry that out to a universal muffler or axle-back system. This would probably be the easiest/cheapest way to go, that is if you can find a universal muffler to your liking.