My mates S2 bonnet use to keep popping without warning, so he fitted pins to his. Then shortly after that mine popped on the M11 - luckily both of us were lucky and we never had it fully lift, but I still didn't like it so I fitted a set of pins aswell.

I only used a cheap pair made by RACERX or something - cost about a tenner. Ally bolts, very lightweight. Took all of half hour to install and for the piece of mind it was worth it