I talked to a guy at a muffler shop a couple of weeks ago and he told me they were crap. BUT, of course they weren't on his list of things he sells. He recommended Thorley's and a couple of others that I don't recall now but they basically were all in the $250 and up range.
I'm in the same place it sounds like you're at, they sound great and the price is right but they're still an unknown.
I'm still inclined to give them a shot with some good locking header bolts and see how they work. In case you hadn't noticed you can also order them ceramic coated. Of course this more than doubles the cost from what I remember.
DON"T DO IT!!! I just spent the better part of a day installing one side of my headers. The clearence on the Flowtech is so small it is not even funny. I usually run a heat shield around my starter, ther is MAYBE 1/4" between the starter and the header. The pain burnt of immediately as well. They do give you very good tone and good responce, but the headache installing them is not worth it in my eye's. I hope my gasket never blows because all my bolts are so round now IF I got them off, they certainly won't go back on. Save your money and buy some Thorleys!!!!
I have a set of afterburners on my car and they fit like a glove, my brother has a set on his 87 truck but they were put on before the motor was installed, and I'm putting them on my 89 truck. They will also be installed when the vorteck goes in. I like them a lot on my car, and my brother likes his. I would buy them again. Just my opinion.
Maybe they work better on newer rigs? I have a 76 Blazer that was a ROYAL pain to install. I had to use straight and 90 degree boot plugwires, alter my linkage for my tranny (automatic), forgo my heat shield on my starter and re-route the wires to the starter between the headers due to the lack of clearance. So, I am not too happy with them but am glad you are!!