Originally Posted by Ludester
The DC header is actually a knock off of the jdm mugen 4-1 header - which is why it flows better and is of such and such design.
The oem jdm itr 4-1 header is a compromise in clearance and performance + packaging constraints.
It is decent for the $ though... especially for ppl in CA who have to keep an oem looking engine bay to keep from getting ref'd and ticketed.