Andy, as my arm pops are usually the front I was wondering if the stronger magnets had any spreading effect on the chassis or if it was just the increased velocity and bigger offs. Have you any scale engineering blue bushings yet? I've yet to have one pop but have only practiced with them not raced. If you were ordering SE also do some nice wizzard compatible gear saver/boss thingies. More reliable because they are a single unit and cannot seperate.