1.) What is the inner diameter of the end of the JDM ITR cat that connects to the b-pipe?

2.) I know the Stock JDM ITR b-pipe is longer than its USDM counterpart. Are there any other differences between the two (ie. piping size, bottlenecks)

 

50 mm or just under 2"

Sorry I don't know.

 

I believe a member on H-T told me when he compared the USDM and the JDM ITR b-pipes that the JDM ITR had bigger piping despite what I have heard people say. There should still be bottlenecks though.

 

jdm itr DOES have bigger piping... its like 60 mm... i am not sure, but it is DEFINETELY bigger than usdm itr piping

 

that would be stupid if it wasnt bigger.
JDM ITR header to the regular USDM ITR b-pipe? errr

 

Hmmm...I could have sworn the JDM cat is not 2.5" throughout. A reputable source said that the ID of the cat piping on the b-pipe connection side reduces to mate with the smaller than 2.5" JDM b-pipe. Can someone confirm.

 

I never said it was 2.5" throughout the whole thing. the JDM ITR header isn't even truely 2.5".

I just said that would be dumb for a JDM ITR motor, with the JDM ITR header of course (which has a collector bigger than the USDM ITR Header).. to eventually go down to a b-pipe the same size of the USDM ITR b-pipe.