I finally got my sound system installed and it sounds pretty good, imo. I put in a Pioneer P7000BT head unit with blue tooth built in, Infinity Kappa 6.5" door components with tweeters, Infinity Reference 5761a 6-channel amp, Rockford Fosgate 1-Farad cap, and a 10" JL Audio 10w3v3 4 ohm model in a sealed build-it-yourself box that had the right volume for the sub.
I wanted to hide my amp from prowling eyes so I built a false floor out of 1/4" thick birch plywood with 3" long dowels for legs. The factory trunk mat sits neatly on top of the new floor.
Total cost was about $800 but I already had the amp and cap.

You can see that the tweeter fit perfectly in the stock location after dremeling out the factory tweeter.

Head unit has AUX in for mp3 player, blue tooth audio player compatibility, blue tooth phone compatibility (how pimp is it to roll up to a stop light, press a button, say "Dominos", and it automatically dials Dominos so you can order dinner, then it goes right back to playing mp3s when you hang up).

The sub box is .7 cubic feet. It is much smaller than my old ported enclosure. It still leaves some space for groceries, etc.