something to remember, when talking cat-backs; there's nothing available for your car (03-up had NO cat-backs available). So you're in reality just talking about mufflers and resonators. Also, not to be a jerk, and understanding that no one is perfect on spelling and grammer... it would help to polish those two area's up a bit guys, a couple posts were on the verge of unreadable. Again, I'm not knocking anyone; it would just be a bit easier to follow and read.
As for mufflers; I like flowmaster's myself, but borla and gibson make good mufflers too (although gibson is more marketed towards trucks, it has a good exhaust note that isn't so loud you'll wake people up driving through a neighborhood at 3am). The flowmaster's, it all depends on what model you get. I have 50 series Delta flow's on my truck; they really arn't that loud. A bit more than I'd want on a 4dr sedan, but still. As was said, check out Hush power.