Transponder Immobiliser

[focced_off]

Not too big an explosion though, just enough to rip their balls off and totally shred their rectum.

You appear to have thought about it in slightly more graphic detail than what was actually necessary.  :lol

I think an Ejector seat would work well too, ideally set off as they enter a bridge (loads of those around London) - plus no explosion, so you wont have to scrub off remnants of balls and rectum from your Head (motors head) !!