The Scorpion muffler support bracket' rubber protectors do contact the underside of the Grab Rail assembly, but that's ok....there is a bit of "vibration" transfer through the seat from the mufflers, but it's not really that noticeable once you get used to it.
The biggest "problem" afaik is the large "U" shaped OEM lower support bracket for the license plate assembly, which does contact the underside of the Scorpion mufflers themselves (not good). I recommend that you do use the replacement bracket supplied in the Scorpion kit, which is flat and gives plenty of clearance between the bracket and the mufflers.
Or...remove the bracket completely and install an FE kit that just attaches to the Scorpion license plate bracket that drops down vertically from the rear of the main muffler support bracket. That's my next project.
As for sound, Yukon_Alex was behind me on his new FZ6 yesterday for about an hour, so he can be an "independent witness" for how loud (or not) my Scorpions are.

In my opinion, yes...they are louder than stock, but not obnoxiously so. They have a nice civilized "burble" at idle that turns into a healthy growl under acceleration. The British really do understand what a motorcycle should sound like.
Did I mention I love my Scorpions? :rockon: