Aftermarket wise, who domestically is making the best 2.5" collector header? I have heard good things about the new Edelbrock header and the new DC header. Are there any other manufacturers making anything reasonable?

 

If you have a JDM ITR with the stock 4-1 2.5" header then putting the DC or a like header is actually a downgrade. I would replace it with a Mugen/Spoon/Toda or better yet, a custom SMS.

 

Why would you consider it a downgrade? I think someone on this board awhile back posted that the DC Jdm was an exact copy of his Mugen header?

 

DC makes a JDM 4-1 thats has a 2.5 collector

 

Downgrade, as in 2 3/8" versus 2 1/2" in collector size won't be noticable on an otherwise stock car. Also, the DC is a copy of the Mugen header only in primary and collector spec. The Mugen has completely different welds as well as inner surface (polished) which make a large difference in airflow efficiency.

Don't get me wrong, the DC JDM 4-1 is perfect for anyone who doesn't have the JDM ITR or better, because it's very similar, slightly larger, and significantly less expensive. I, myself, choose the DC of the ITR just because of that, but Financial Guy already has the JDM ITR so it is not cost-efficient IMO.