Thing is, they are not THAT loud when just low revving. Spank it though and you'll wake the dead! Just don't do that where you are going to draw unwanted attention.
My wife has carbon Termis on her MOnster 620. They were a lot cheaper at £400 (Ducati Performance cans, but were actually Termis), and possibly because it is a 2 valver it is a lot more mellow. The 4 valve motors do tend to have more of a raw mettalic quality to them. I just did a track day at Cadwell and my wife was taking pictures and a bit of video. You can clearly pick the one exhaust note out of all the UJM (Universal Japanese Motorcycles) that I am riding past with.
The video clip is on that page.
http://82.70.86.166/hand/bikes/index...ll20050325.php