I'm no expert on DC headers and I was given this one basically for free cause there is some substantial damage to the bottom tubes on the underside. The kid I got it from told me it came off a crashed GSR-swapped LS but I've since had a few people tell me it's the JDM ITR only race header. I always thought the DC 'race' headers were big long 1-piece contraptions that delete the cat and have built in resonators/flex pipe, etc(?)... I checked all over DC's website but it's very vague on details and specs on anything- not exacly helpful. I measured the collector on my gf's DC header and it's only like 2.0" OD, the collector on this one is like 2.4" OD and the outlet is 2.5" ID Anyone??