Gibson is the way I'm leaning having used them before(they are the quietest without sacrifing flow).I'm going to check the $$ difference of buying just the muffler and having it done or just buying the kit.A lot of people like Flowmaster.Iv'e used DynoMax before(they are tested to flow better than Flowmaster below 3500rpm)on a 2 V8 Dakotas and on my GW.I found that case length(shorter = louder) determines your sound/noise level.
Borla is a high quality part made of polished stainless.
I have the Borla catback on my stang and I like it. It has a nice mellow tone. When I decided to buy mine I kept an eye out in magazines and found it for half the price (supposely had some kind of defect though I haven't seen any or had any exhaust leaks and I've had it 4 years). It just depends on your preference whether you want to risk something like that or not but the good thing about stainless is that you don't need to worry about it rusting out.