I like mine so much that when they were damaged in the accident I didn't even consider replacing them with something else. They make great power and low end tq as well and never dragged mine except 1 time, when the bike was knocked out from under me.
I scrape mine a little weekly, it will make contact a moment before the floorbaord if my suspension is compressing at all.. The contact point is the collection chamber, it can only be seen on the bottom of the heat shield cover.
No added vibration noted
+1 on that. The scrape is low, so you need to be down low to see the spot on the bottom of the x-collection chamber. 1st time it happened it really woke me up! Since the 1st time, I've put Harley Goodies floorboard exetenders on, so I have a bit more warning now that I'm getting close.