I did that American mod and cut the 'peashooter' off the end. sounds much nicer, a little louder, but more rumble and pop on over-run.
I used a grinder to cut of the welded bolts not a dremel from inside of the pipe. the bolts turn fine after you cut a groove with a saw and turn with screwdriver. note - grinders are not the most delicate tools and it shows.
but I feel safer now commuting as the deeper noise seems to carry. my parents say they can hear me coming up the valley where they live, where most bikes are heard for a second then pass.
don't know if that's true I'm always doing my Meatloaf impression when riding up the roads round there!
(the police van that's usualy parked out side their house does make them slow down rapidly when they come over the crown of the hill
)