It's a '98 model with bose and delta cc...does it have a subwoofer somewhere?(I mean a stock one)
P.S. I serviced the tranny but the little thumps at low speed are still there...who cares?? It's not so bad and I can live with them.

check on the rear deck. You can see them from the inside of the trunk. They have two black covers on them. Listen in the back, you should only hear bass comming from the top rear deck speakers.