bogus wrote:
the adaptors won't help with new speakers.

Here is what I would do - and to do it right... it will only take time... it's not hard, just a time suck...

1. remove the old head unit.
2. remove the radio brain unit - this is more than likely in the dash behind the glovebox.
3. there is a harness at the brain unit, use that for power to the new head unit.
4. remove all four speakers. I suggest removing the seats and the carpets. This will make running cable that much easier.
5. remove the battery, drill a hole through the firewall to feed power to the amp. Use 4 gauge and then get an 8 gauge step down for the amp. This way, if you ever want to upgrade, you don't have to replace the main power and ground leads. Most car stereo shops have the tool necessary to put a crimp connector on the 4 gauge. Have them do one end each. Get 15' of both - red and black, to reach the back of the storage area.
6. screw down the new amp on the rear vertical bulkhead. This will keep it in open air and still be out of the way.
7. screw down the power junction boxes and run accordingly
8. run the RCA cable from the head to the amp down the transmission tunnel.
9. Run the power wire under the driverside sill... there is a little notch in there that will dress up the 8 gauge wires very nicely and keep them safe.
10. You will need a big fuse at some point in this process, 100 amp is perfect
11. run the speaker wires from the back to the front, down the passenger side of the car.
12. you will need to hack up the bose speaker boxes to accept your new speakers

I am sure there is more... but this will get you going!