i placed my subs facing up in the trunk of my bmw 740i, the whole rear deck of the car is cut opened to expose the subs and the port since they both face up, and the trunk is now totally sealed making it feel like a hatch back car. we sealed this cos we have 6amps and 4lcd monitors installed in the trunk to give it nice show effect. the subs sounds great, its a XXX15 8500RMS driven but 2 linked earthquake PHD10,000 amps etc... would there be any other better way to install a sub this powerful in output and yet been able to make the fantastic rear design without cause any damage from direct sub for, vibration etc...