I like the disc clutches best. I just got back into karting this year, but use to run Bully clutches. I got an AKRA and was told that the drums were fine for the motors. I ran the drum for about a month and a half and sold it. I was getting killed on the starts and sometimes it would chug. I maintained the clutch like the instructions said, but never could get it to quit. Might have just been a bad apple, I dont know, but I threw my Bully on from 2007 and have been running it the rest of the season and still going. Just my .02 cents.