[thstone]

I would suggest that you pull the rear storage compartment from the car (be sure to disconnect the speaker cable connector) and verify what speakers you will need for the upgrade. I have seen several different configurations of number and size of speakers fitted to the rear storage compartment depending on whether it was an early factory install, later dealer install, or an aftermarket part (the rear compartment and the speakers were sold for quite awhile as a factory kit and then later as DIY kits on eBay).

The dash speakers are 4" three-way speakers. They can be replaced with any model of equivlaent speaker (whatever you want to $pend). I posted a good DIY for replacing the dash speakers in the DIY section of the forum.

I believe that the head unit and the amp have to be replaced as a pair because of the optical interface but someone else can verify that statement.