In considering the design for an audio system in the STI, I’ve come across of a couple of pretty slick items. Space is obviously a concern, since having a trunk means learning to use the trunk. Fiberglass is obviously a nice choice considering the reduced weight compared to wood. Audio Integrations makes a couple of really slick items for the car:
A 12″ Subwoofer Enclosure and an Amplifier Rack, both designed specifically for the car.