Guys,

Is the USDM ITR catback same 2.5" as JDM ITR

 

I think they are both 2.25"

 

i think us is 2.25 and jdm is 2.5.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smooz EK &raquo;</TD></TR><TR><TD CLASS="quote">i think us is 2.25 and jdm is 2.5.</TD></TR></TABLE>
x2

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdm_bones &raquo;</TD></TR><TR><TD CLASS="quote">x2 </TD></TR></TABLE>

x3

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smooz EK &raquo;</TD></TR><TR><TD CLASS="quote">i think us is 2.25 and jdm is 2.5.</TD></TR></TABLE>

This has been stated on a number of occasions throughout the years, but I don't ever recall seeing any conclusive proof to either confirm or deny it. I'm not saying it isn't true (though I have some doubt), but if anything, it would make more sense if the JDM version were 60mm OD like the vast majority of Japanese performance systems for the car.

 

USDM is 2.25"
JDM is 2.36"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smooz EK &raquo;</TD></TR><TR><TD CLASS="quote">i think us is 2.25 and jdm is 2.5.</TD></TR></TABLE>

 

USDM was claimed it was 2.5'' but it actually isnt. IDK for shure what either really is.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tegG2 &raquo;</TD></TR><TR><TD CLASS="quote">USDM was claimed it was 2.5'' but it actually isnt. IDK for shure what either really is. </TD></TR></TABLE>

USDM is 2.25" OD with several smaller "bottlenecks". This has been confirmed by many individuals (myself included).

 

any difference in performance? benefits if hooked up to 91 b18a?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tegG2 &raquo;</TD></TR><TR><TD CLASS="quote">USDM was claimed it was 2.5'' but it actually isnt. IDK for shure what either really is. </TD></TR></TABLE>


probably the OD

ID:

usdm: 2.25

jdm: 2.36

jdm header collector is 2.5 guys. Same as the inlet for the jdm cat. But the rest of the system is 2.36 ID.

 

so would the USDM ITR complete piping and muffler fit on a GSR cat converter?

 

No, the ITR piping is about 2 inches longer than GSR piping.

The b-pipe is equivalent to the length of an LS b-pipe.