Your confusion is due to the fact that the picture shown is for a header on a FWD car. most likley a 90's honda due to it curving back on itself (exhaust side of pre "K" motors are facing the front of the car). The DC Sports S13 header looks like this:
http://cgi.ebay.com/ebaymotors...&rd=1
Now between the 2 companies, I would probably go with DC Sports. When I was into Honda's I found their products to be far superior to OBX's, but then again, that was with Honda's
Also make sure you check out Hotshot headers as well. Good product.
Hope this all helped, good luck!