rev are you sure someone did that? i seriously think that much voltage running through the box would mess with the signals put out by the amps or speakers. not to mention drain the battery. i suppose it might be possible, but i'm still skeptical.
--(keep in mind that during the holocaust the concentration camps used 400,000V to keep the jews in. that was enough to melt skin. a decent 1000-5000 burst would blow you hand back and tighten up the muscles in your arm for a few seconds)
anywho... personally, i'm thinking of making the bottom piece of the box cut so they fit tightly against the wheel well of the trunk. (where it kinds curves in a little) so you'd be yank'n on the box trying to get it out, but it won't budge unless you take it apart. (by which time the thief gets ye ol' crow bar to the side of his knee....

( or get jackal to send a few SAW warning shots by him... LOL)