A lot of people go with the OBX header because of the price, and the gains on it are actually very good as well. They replicated the Cossie headers, with very good welds and craftsmanship. i've seen em first hand and I was very surprised. The only thing I would suggest is getting better gaskets, (like 12 bucks or so from fswerks or a performance shop) because the gaskets that come with 'em aren't the best besides the the header it self is the best bang for its buck, and you also get both flex pipes atx and mtx, so you can sell the on you dont need for a couple bucks to pay the shipping lol. But you can't go wrong with those headers.
and remember you still have to coat the headers or wrap them. And a tune will defiantly be a must sooner or later.
2005 Focus St for sell
2003 Silver focus SVT project - i'm giving it away
2005 silver focus S 2.0 dura BEAT to SH** lol and still going