American Thunder Vs. Custom Duals

I'm at an impasse and I want to get some input from you guys (and gals). I just bought Headers and a Y-pipe for my 87 Trans Am (350 V8), and now I'm not sure what to do next. My original plan was to have a custom dual exhaust built for the car, but it seems that its gonna be mighty expensive to do ($900 is the best offer I've gotten around here). I only picked up the Y-pipe so I could hook up the stock exhaust untill the new dual was funded. But now I see that Flowmaster has a bolt-on catback system for much less that I can afford now, and do the whole thing (headers back) by this weekend. I know that I'll get more horse from a true dual system, but is it enough to be worth the almost $600 in difference? I also know that the Flowmaster sys has mandrel bends, and the place that wants to do the custom job won't. Lookin for any thoughts you may have, thanks!

true duals will definatly increase performance, 40 series mufflers would suit you best if your looking for a mean deep sound, but if your looking for something to hold you over til you get the green, you can get a spintech muffler for $119 for 82-92 trans am's. sounds damn good. and has a powerful
and agressive sound.

are you a serious racer or just want to have more oomph
if you are serious then get the tduals
if you just want a nice rumble and some more get up and go than the flowmaster will do you fine