I'm feeling creative this morning - here's another idea:

Get a 12v compressor and install it in the truck. Fashion an air nozzle and attach it to the rear bumper. Connect the compressor to the nozzle via a switched valve, so you can hit the switch whenever you need some jet assist.

The problem would be the limited amount of time, but that can be increased by installing multiple compressors hooked to multiple tanks that can be sequentially switched - sort of a poor man's pulse jet.

If you wanted to add a sense of realism to the idea, you could inject compressed methane gas into the tanks for sequential release and include audio piped through external speakers. <img src="/forums/images/graemlins/wink.gif" alt="" />

Frank <img src="/forums/images/graemlins/cheers.gif" alt="" />