The JDM header is 4-1 and has an 2.5inch collector. IS the cat of the jdm modell better flowing? What would I need to mount an jdm header to an usdm exhaust system? Better using an jdm cat too? Whats about b-pipe and axle back? same as usdm or also different?

 

from what i understand usdm b pipe is 2 1/4 piping and jdm b pipe is 2.38...i dont think the jdm header will bolt up to the us cat..im not sure though

 

the jdm header will not bolt up to the usdm cat. i have a jdm header and u either need to buy a custom cat from carsound or get a jdm cat. if u need a cat for ur headers i am selling one. i have a carsound cat that will fit directly to ur jdm header to ur usdm exhaust. my email address is orele28@aol.com

 

Are you sure a JDM cat will not bolt up to a USDM header, i was always under the impression that it was the exhaust that would not bolt up as it was too long. USDM cats are 17" long, JDM cats are 12" long, which means JDM exhaust b-pipes have to be shortened by 5" to fit up to the cat on a USDM car. i asked someone a while back to measure their USDM header and it was the same height/lenght as my JDM (OE) header. So if thats correct a JDM header will bolt onto a USDM cat without any problems. I fitted a DC JDM 4-1 header to my last Si Integra and it still made a perfect seal with my stock JDM cat even though the collector donut was approx 0.25" too big

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mugenracer &raquo;</TD></TR><TR><TD CLASS="quote">Are you sure a JDM cat will not bolt up to a USDM header, i was always under the impression that it was the exhaust that would not bolt up as it was too long. USDM cats are 17" long, JDM cats are 12" long, which means JDM exhaust b-pipes have to be shortened by 5" to fit up to the cat on a USDM car. i asked someone a while back to measure their USDM header and it was the same height/lenght as my JDM (OE) header. So if thats correct a JDM header will bolt onto a USDM cat without any problems. I fitted a DC JDM 4-1 header to my last Si Integra and it still made a perfect seal with my stock JDM cat even though the collector donut was approx 0.25" too big</TD></TR></TABLE>

Diameter wise, the JDM Cat will NOT fit up to the USDM header. A new flange would have to be added to make it work.

I had a jdm cat from a swap that was done to a friend's car, and it did not fit with a stock USDM ITR header (on another friends car) as we lined them up while the car was on a lift.