I've had the stocker, supertrapp, luftmeister and now a MAC on my K75s. The supertrapp was awful on so many levels, looks, tone, too short so the back wheel got smoked. The lufty was nice but not too well made and needed repacking often. Most interesting was when cruising with another K75 the bikes harmonized, the exhaust notes canceling then re-enforcing each other. Cruising next to a K100 did not have the effect. Really like the MAC i'm running now, nice and mellow. Performance is a wash with all of them except the s-trap, which actually hurt the mid and top end, but I hated the whine of the stocker and it is a homely overweight hunk of German engineering to boot.
