Its pretty bad inside or out, when the pipes are cold good God almighty. Car with alarms in parking garages fear me.
It drones pretty bad too. My GF complains her ears are gonna pop if you don't put in the clutch and take your foot off the gas while slowing down. It does get a lot of attention and overall highway crusiing isn't too bad as long as you keep it below 75mph. I rarely do though as the flow of traffic here (when were not parked) is 80+ and then you get the drone pretty bad.
PM me if ya want to hear it I'm more than happy to give you a live demo on my cell.
Hightower also has one as well as two guys in the NY chapter.
Bolt up was pretty simple but it hags low as I think the hangers are a bit too long. Other than that it installs pretty easily.
Link for Pic:
BOSAL