(thumb) that looks great! The only thing I'd change is perhaps move the sub to one corner to free up a little bit of room. Are you going to make a plexiglass cover or anything to cover up the amp when you have stuff in the trunk?
Looks clean! I would paint the sub grille black, but that is my only suggestion. Good work!
dude, the floor looks great but you gotta match the sub carpet to the rest of it... that's the only thing that I can complain about. One thing you may want to look into is doing some kind of lexan cover for the amp rather than all out plexi. Lexan doesn't scratch as easily and you can get it thinner. In terms of keeping the amp cool you route out some vents in the lexan to help the heat escape. Excellent job overall though considering this is your first attempt at custom work!