Not sure what the crash bung spinning would achieve??! The main concern is that the bolt holding the crash bung on bends in the event of an impact, rather than shears off.
PDQ based in Maidenhead. They know there stuff! The sliders are actually GSG Moto which is a german company but you can't buy from them direct for some reason (well you cant on their website) PDQ are an official stockest for them so if youre interested give them a call