Headers/Complete Exhaust System ?????
I think that any header has the potential to be drop in.
The problem is that the jigs they use to produce the headers wear out fast. The first 50 sets might be perfect, then they start going donwhill.
I have a cheap brand X $79 set, and with the exception of a slight bit of idler arm contact on the right side, they fit around everything perfectly (even power steering box).