i'm in the process of completing my jdm h22a install and ran into a problem. i have the jdm exhaust collector and downpipe and tried matching it up to my usdm h23a1 cat and the bolts wont match up. i know that the jdm h22 downpipe has bigger piping than the usdm h22 downpipe, so i'm assuming thats where my problem is. for all of you who have done an jdm h22 swap into a usdm si, did you guys use the jdm header and downpipe with your old cat and exhaust or did you guys buy new stuff? what would be the easiest way for me to fix this? to buy a larger diameter cat?