If Kooks, ARH or Stainless Works goes out of business, who is OBX going to copy? Then they go out of business too and you have no headers to choose from. Like already mentioned, you pay more for Kooks, ARH and SW because the other stuff is all copies of the expensive stuff that is made in China. I don't know about you guys, but you can afford anything you want, especially a $1300 exhaust SYSTEM (headers and midpipe) if you just SAVE. But we are America, we don't save an we want instant gratification, that's why China OWNS us now.
There is more to just fitment when you purchase a header, the primary and collector design have an effect in scavenging which help reduce pumping losses of the engine which in turn helps the car make more power and be more efficient. That's why in one of the 3v header tests done a few years ago, Kooks, ARH or SW (can't remember which one off the top of my head) made more power then all the other brands. The BBK's and Mac's fit ok, but the other brands do more then just fit.
This is just my opinion and some of my experiences, hope that some of you take some of the info in this thread into consideration and help support the companies and people who actually help our hobby grow.