I have read up on most if not all the exhaust threads and still need a bit of guidance. I plan to run a JDM 4-1 header w/ 2.5in(?mm) collector to a 2.5in(?mm) cat from smsp to a 63mm T1R b-pipe but I have not decided what exhaust I want to run. So here is my question: Is the mm size of the collector on the JDM 4-1 header 63mm outer diameter? I would like to keep the exhaust a constant size like 63mm outer diameter from the collector back. But most of the exhausts I have come across are 60mm(like the Spoon Sports exhaust). Would this be okay to run even if I have been running 63mm from the collector or will a smaller exhaust diameter at the end gum up the flow and hurt performance? Any suggestions would be appreciated!

 

3 mm at the tail end won't be an issue

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITR3 &raquo;</TD></TR><TR><TD CLASS="quote">I plan to run a JDM 4-1 header w/ 2.5in(?mm) collector to a 2.5in(?mm) cat from smsp to a 63mm T1R b-pipe but I have not decided what exhaust I want to run. </TD></TR></TABLE>

You've apparently decided on the "exhaust", all you need now is the axle-back/muffler.

 

Thanks alot. The JDM ITR header does come with a 2.5 inch collector right? Also i was looking at an Apex-i N1 exhaust. Does anyone know if that will bolt up to the 63mm T1R b-pipe since the Apex-i muffler only has a 60mm inlet or should i try to source a JDM Apex-i N1? Thanks again for the help!

 

I had 4-1 2.5" header and T1R b-pipe and Spoon N1.

it's really good set up if you dont mind the noise