or you can save the trouble and go buy a shallow mount box from JB or stathfield. should fit behind the seats
My car audio:
CD tuner: Alpine CDA-9884E with Ipod interface
Front speakers: Alpine Type R SPR-17S 6.5 component speakers, powered by a avant-garde 23dxi 2 channel amplifier - 2x51 watt RMS
Rear speakers: pioneer coaxials connected to tuner
Subwoofer: Alpine Type R SWR-1222D 12" 2 ohm dual voice coil 500 watts RMS powered by a response precision 2x150 watts RMS 2 channel amp bridged to 500 watts RMS @ 4 ohms