as the topic stated i got some free US itr headers and cams. i have the itr cat back will everything go in correctly. ive done a search and it says it will. thing is. i want to get dc headers 41 for my car. i heard the jdm dc headers is 2.5" at the cat. and the itr cat back is 2.25". will the cat back be restrict the headers?? or should i stick with the US itr headers?? i want to keep my car near stock looking. well the exterior at least. any help will do. TIA

 

what mods have you done besides the ones you listed? you don't need 2.5" if you just have bolt-ons. The catback will not be restricted by the header.

I say get jdm itr 4-1 header and add heatshield. looks stock both inside and outside.