i guess
for a headrest to apply enough force to actaully do anything besides make the kids think its a game of duck, duck goose.....there better be like a 2,000 psi pneumatic pump in the trunk. i mean, how far does a head rest travel? 5..6 inches? it would feel like dropping a grape on the top of my head.
get some firepower, make the annoying bastards cry a little