I have a 99EK with a B swap and a GSR header with the 2.5" collector. I'm going for a RSR GT2 ExMag but I'm not sure if it'll fit the collector since it's only a 2.34" or w/e that measurement is. I just want to know if they'll mate and if I need to buy a test pipe with it. Thanks in advance!

 

Normally no, but mine does since I modified it. It's for sale too.
http://www.hondamarketplace.co...42017

The section I chopped off had a bottleneck at the collector since it was intended for a D series motor. Look at the 2nd to the last picture and you'll see it. That section was cut and replaced with a 2.5" high flow cat (swappable to a 2.5" test pipe) after expanding the 60MM pipe slightly to 2.5" and welding a 3 bolt flange on it. I have a B18C5 with the 98 spec JDM ITR 4-1 header. Bolts up just fine and sounds amazing!

 

So I'm going to need to buy a test pipe and have the piping customized?
Would it be easier buying a new header? Probably not, argh.
Alright well, thank you!