I'd be pissed off too...
It is so funny how people get defensive when you are clearly stating that there is a problem with your new HIGH DOLLAR headers! I'm sorry, but for all the crap people talk about these headers, and their price THEY SHOULD BOLT RIGHT UP!! Suggesting that your frame is tweaked,
give me a f'in break...
As for the quality of the Doug's headers, I would say that they are second to none. They are obviously of higher quality than the Hooker Super comps I just put on my car. AND they dont hang down as low. With the SC's though, everything just bolted right up. No interference with anything, and my stock oil filter and housing fit fine. All the bolts were easy to get to, and I had both sides in after one night (5-10pm).
I have a friend that just purchased a set of Doug's for his '67 GTO. They appear to fit well. Of course, no one mentioned to him that he would need to move his disc brake proportioning valve in order for them to fit. What a major PITA! Of course, once he re-works his brake lines they will fit fine but thats alot of work.