Traded this, it's gone!
I still have a custom sub box I made for my old car. It will fit any 02-07 Impreza sedan, and can probably be easily adapted to work in other cars as well. It fits a single 12" sub, the interior air space is 1.6 cu/ft. I built it with a notched back to fit with a rear strut brace. There are metal straps that attach to existing bolts under the back seat. It has internal bracing and it is built completely out of 3/4" MDF. It's very solid and it fits perfectly in the trunk. You can mount your amp to the back of it, which can be easily accessed by opening the pass through on the back seat. Also included are the carpeted trim board that attaches to the front of the box, the grill shown, and the floor piece that goes over the stock carpet. You can still access the spare tire as shown in the pics. I would like $75 for the whole setup, sub not included. If you need a sub I have a couple to choose from that work well in the box. One is a Boston Acoustics, the other is OZ Audio.
This is what you see with the trunk open, there's still a lot of useable space.
Still have access to the spare.
