I have the full B&B system Headers, high flow cats, and cat back. I love the sound, but it is LOUD. Not as loud as any system aftermarket system with no cats, but very loud. I would say in order of sound level, not sound quality, from quietest to loudest:
Snake-oyl Rear sub replacement
Borla
Corsa
B&B
TNT
I have not heard the Belanger system in person.
I recorded the db on a meter while dyno testing. I was about 20 feet away, but still in the same building. Being in the building I am sure made the sound seem even louder, but I recorded 117 db on the meter when he hit 6,000 RPM at WOT. That is loud by anyone's standard. I have seriously been thinking about ways to quiet it back down. The sound quality is great. I like it much better than any other Viper exhaust system I have heard, but I just need a way to take it down a few notches.