I'm going to try and mess around with some fiberglass and mdf for a custom enclosure behind the seats. I'm going to be making a frame out of mdf like in the picture below, and then pulling fleece over it all and adding 7 layers of glass on top of it. depending on how much work it might be i'll either take the easy way out and carpet, or finish and paint with the same texture that's on the dash.
i plan to put 2 Exile 10" shallow mounts into it. they have a mounting depth of only 3.5 inches and i heard them in a buddy's car, and they sounded awesome....
[Broken External Image]: