I just ordered my mugen header and i was wondering if i had to replace the cat or exhuast i am hoping to use the stock exhuast and cat will it line up?

 

There are 2 versions: JDM and USDM.
USDM version will plug and play.

 

USDM=2inch collector
JDM=2.5inch collector

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDMluvR &raquo;</TD></TR><TR><TD CLASS="quote">USDM=2inch collector
JDM=2.5inch collector </TD></TR></TABLE>

I could be wrong but I thought USDM was 2.25 inch. I would suggest that you get an aftermarket cat, if the header is 2.5inch, instead of modifying your stock one. A stock cat from Acura can be as expensive as $800CAD but I got a Vibrant for like $75CAD for my set up. To be installed Monday. Even if it sucks, it's chump change compared to replacing OEM. Just a thought. The collector has to be a near perfect fit to the cat but the exhaust doesn't have to be.

 

like they said,

USDM is 2.25"
JDM is 2.5"

The USDM stock ones all have a flange size of 2.25" so if you picked up a JDM Mugen Header, you're going to have to compensate for the difference in flanges sizes by either welding a 2.5" collector on one end of the cat and then leaving the 2.25" USDM exhaust or you can get a high flow cat and get an exhaust at the same time. Go figure

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nvious R &raquo;</TD></TR><TR><TD CLASS="quote">like they said,

USDM is 2.25"
JDM is 2.5"

The USDM stock ones all have a flange size of 2.25" so if you picked up a JDM Mugen Header, you're going to have to compensate for the difference in flanges sizes by either welding a 2.5" collector on one end of the cat and then leaving the 2.25" USDM exhaust or you can get a high flow cat and get an exhaust at the same time. Go figure</TD></TR></TABLE>

Like we said, USDM header flange OD= 1.97 inch (50mm), JDM header OD = 2.56" (65mm)
USDM exhaust OD = 2.25" (57mm), not the flange of the header!!!!!!!!!!!!!!!!
Same applies for Euro spec.

 

yeah.. i knew that.

 

jdm should be ran with no exhaust, and if you run exhaust, run no cat

south carolina rules

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Stunna Ben &raquo;</TD></TR><TR><TD CLASS="quote">jdm should be ran with no exhaust, and if you run exhaust, run no cat
</TD></TR></TABLE>

I don't really agree with that at all. It has been proven that a high flow cat makes near the same hp (~1-2 hp) compared to a test pipe. It also puts out less emissions and you don't stink like gas, and while it still sounds pretty bad, its no where near as bad as a straight pipe or open header!

 

so when it gets down to it i wanna put my header on i will need to get a aftermarket cat when i do want to put my cat on and bolt it right on and get my exhuast and bolt it right on
any suggestions and aftermarket cats and exhuasts that will BOLT right up?
i kinda wanna keep my stock catback i just wanna change the cat and header how do i do it?????????????

 

Adding a header and high-flow cat to your stock exhaust is almost useless unless you get the bottlenecks removed from the stock b-pipe.