Thanks for the help!
Ive yet to pull my almost new Vee apart to have a look. The door speakers are relatively easy, but Im sure the rears are a little trickier. The plan would be to use something like MB Quart reference components in the front (either 4" or 5.25" in the door, and possibly tweeters - how hard is it to remove the std ones in the dash?), and then 6x9s for the rear.
Ive got some old Nachamichi (sp?) amps kicking around, one of which could go under the drivers seat, or maybe a Genesis 4ch amp. But the first step is really to just uprate the speakers...