Hey Bob, I run some carbon slip-ons on my '99 that were sold as Ducati Performance. Not sure if they are the same manufacturer as the ones you are looking for, but mine are not very loud, sort of a subdued rumble until about 8000 rpm then a loud machine gun like sound. The rumble does carry quite a distance, however. I let a friend ride mine and heard him for quite a long time and was very surprised. Don't know if that helps you, but my two cents..
