I installed a Kenwood unit in place of the stock cassette stereo. I purchased an install kit Gregg mentions from Crutchfield. If you buy theirs

you get the trimplate that Gregg mention in addition to 2 wiring harnesses that mate to the stock Volvo ones, directions and wiring diagrams. Both harnesses attach to the wires that are coming out the cd receiver you choose. The harness for constant power/ignition on power/antenna/illum.

mates to the connector in the radio cavity that the stock unit was plugged into. The other harness plugs into the connector that you unplug from the

factory amp and feeds the speakers in each door. No cutting of the stock

wiring is required going this route. And within 30 minutes or less I could put the stock unit back in. I highly recommend the Crutchfield kit. And like JohnB said, after doing this the weak link will then be your stock paper cone speakers. I replaced the fronts with Boston Acoustics 5 1/4's

and Polk 5 1/4's in the rear. Sound is very clean for not having an amp.

And base is quite good considering no subwoofer. If i were to add anything it would be a CD changer. Good luck.