i just purchased my first volvo, it's a 2001 s60. i may have the premium sound package but i'm not shure, first how do i tell? i took off the center speaker console and there is a space for a tweeter and a wire that looks to be plugged into something in there. also no speakers in the rear shelf, but there are some wires there as well. no amp under the passenger's seat. what would be a good way to upgrade without strarting from scratch? ALso what are those long thin rectangle shaped grates on either side of the dash?

you can tell by reading the code on the radio.

easy way to upgrade is to actually start from scratch. you'll get better results and less headaches. it doesnt have to cost an arm and a leg if you plan it out.