I wanna know what size is the piping for a stock Type R exhaust system? Is it 2.5"?

 

USDM ITR is 2.25" OD, with bottlenecks at the connecting joints.

JDM ITR is 2.5" OD, tapered to 2.25" OD I believe, with the same bottlenecks as the USDM ITR.

Dont get the 2.5" confused with the size of many aftermarket peices, the piping thickness on the OEM exhaust is fairly thick, ID is close to 2.36"...or somewhere in that range.

 

Would it be wise to get a 2.5" piping for an ITR engine w/ basic bolt-ons. My header has a 2.5" collector. I'm trying to decide what size catback system i should get.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blkcivicpn0i &raquo;</TD></TR><TR><TD CLASS="quote">Would it be wise to get a 2.5" piping for an ITR engine w/ basic bolt-ons. My header has a 2.5" collector. I'm trying to decide what size catback system i should get.</TD></TR></TABLE>

I think so. 2.5" systems work well on stock/mildly built ITR's.

This is my dyno of a before/after of stock VS JDM 4-1 + resonated testpipe + T1R catback.

Baseline is stock ITR, the two higher runs are back to back runs, no tuning, same day as the baseline, same dyno...etc etc.