I have the Vibrant and I can tell you that EVERYBODY comments on how sweet my car sounds. People who don't even care about custom cars comment on it. I have even had a couple people tell me it makes my car sound like a V8. On the other hand, it's EXTREMELY loud on the highway and any speed over 50. If you do a lot of highway driving it may irritate you.
I've had one for a while now, too. It's an excellent system, the quality is absolutely top-notch! The sound is awesome, and I really like the way it burbles and gurgles in off-throttle situations, too.
I have a vibrant with a FC race header and it was loud! I had a resonator put in and it quited it down alot. I would go for it. WIht the race header it will be loud though. I do get alot of compliments on it though. Try the FS quiet system if you want something really quiet.