I've got some good leads on replacement units from the guys above. I was thinking of putting in a power amp, but now think I'll just go with a strong aftermarket piece with usb and aux in in the front. That should fix it, and I should get a little more power out of it. I don't know how to measure it, but the factory HU sound like ~15w rms. A unit with 20w should sound good without blowing the voice coils out of the factory speakers; the car came with the factory subwoofer, so whatever the premium system was in 2003, I've got it.