in my brothers Au, hes forfieted his boot and spare wheel completly. Theres a custom made box that fits into the spare wheel hole, and is then level with the boot opening. in it is a single "cerwin vega" 15" some massive capacitor and several rediculous amp's. all finnished off in seemless black vinal, fitting flush with the top of the amps, cap, and sub. before this and the rest of the stuff was installed the car was totaly gutted and had those tar sheets installed all thoughout doors, floors, roof, firewall, boot floor sides and lid. all up cost about 20g, but its shocking how much this one sub puts out. and with all that sound deadening it still shakes the house windows on half voliume. and when the stereo is off, what impresses me more is how friggen quiet the drive is now!