http://www.youtube.com/watch?v=xFZbb03Jg4c
a dopey video of my Flowmaster American Thunder cat-back. It's right at that point of being loud but not loud enough to get pulled over for. Inside the car it's kind of annoying with that flowmaster drone but you can hold a conversation without having to speak louder than normal.
As for it being "fast" my car has trapped 120mph naturally aspirated through it but when spraying it starts to really show it's restriction. 125-126mph is about all the car will do through the exhaust and opening up the cutout gives big gains...