Uhm, is it factory? If so it sounds like they ran a box off the head unit. If they did, trash it, probably blew out the two rear channels.

Are you thinking of doing the same? Please don't, it will sound like ass and blow your headunit (if it isn't already)

To remove it you have to remove the trim around the HAVC and Radio (one piece, just pull it off) and move your center console backwards (2 bolts on the back R/L, take out your ashtray, 2 bolts in there) then there are 4 bolts holding the radio and storage tray in (or just the radio if you have the double din cd/tape unit)

always remember we don't have grounds in our harness, so you'll have to body ground it.