I recently purchased an itr header off ebay, i'm not totally sure if it's jdm or not. It's 4-2-1 and the od of the collector is 2.5" i think it's a 96-97 jdm but i don't know for sure. can anyone help? here is a picture of it
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=33632&item=2468986816&sspagename=STRK%3AMEBWN%3AIT

No, that is not a JDM header. That header is out of the USDM Type-R. It is not the same. The JDM header is a 4-1 1piece.. If you where expecting a JDM, well, it happens... But just remember this next time: If it sounds too good to be true, then maybe its not...

always see pics of what your buying of ebay, people are forever tryin to scam on there. Check with ebay i know the have a safeharbor policy aginst fraudulant sales on there. worth a shot !!

actually the seller never said that it was jdm, i was really only looking for a type r, i didn't really care if it was jdm or not. It will give me performace gains compared to my stock ls headers. also, i'm pretty sure that in 96-97 they made 4-2-1 jdm itr headers. i know that 98-01 are 4-1

well i guess it didnt matter then

No, that is not a JDM header. That header is out of the USDM Type-R. It is not the same. The JDM header is a 4-1 1piece.. If you where expecting a JDM, well, it happens... But just remember this next time: If it sounds too good to be true, then maybe its not...
More than likely it is a USDM header, but only the 98+ ITRs had the 4-1 design with the 2.5 collector, 96-97 had the normal 4-2-1 like the USDM with 2 collector.

do all of the usdm's have 2" collectors? i measured my itr collector to be 2.5" outer diameter and about 2.3" inner diameter. it's definetely bigger than 2.0"