Originally Posted by ImpulseITR
Would it be possible to modify my aftermarket cat to fit the header, ie widening the flange? I wasn't sure if there was enough room to play with it. If so, can a normal muffler shop do the work? Also, what is the cheapest place to find a header, (I am leaning towards a JDM DC 4-1)?
You cannot modify the OEM USDM cat because your cat will need to be a different length.
However, if your aftermraket cat is a Carsound or similar cat designed for the specific purpose, then you can have someone like SMSP create the flanges you need to connect your DC JDM header to your USDM OEM exhaust.
Dave might actually have cats in stock that he could easily modify.
Also, just a brief comment about header choices.
I think you'll save money, over all, if you keep your end game in mind and thoroughly planned out.
If
all you want to do is a header and exhaust, then your choice of the DC JDM is a very good ones. Even with the header connected to the restrictive OEM USDM exhaust, you will be able to feel the difference. The header will also be fine if you decide to go with a 2.5" exhaust later on.
However, if you want to do a lot to the car (the current Allmotor trend is hard to resist), then you might want to go upscale with the header. It is expensive, but if your end game involves a lot of building, you will want to replace the header.
For a bolt on modification that makes observable power, however, you really can't beat the DC JDM (or OEM JDM) headers.