have u ever considered installing those... idk their name off my head, but its something like, pain siren alarm or some crap like that. ive read they sound like those damn fire things that schools have, which are freakin loud as hell and very small in size. now u could install one of those hidden in the airvents aimed towards the driver side and another one aimed to the passanger side, lmao. they wont kno what hit them
edit: heres what i was talking of http://www.sonicelectronix.com/item_5367_Directed+513T.html