Its easy to do but takes some patience. Since STS = Bose you need a replacement speaker and they don't seem to be real easy to find, although you may be able to get one from Bose directly. The center speaker on my 99 started buzzing and I replaced it with a regular 3 1/2" - there are mounts for both. Remove the A-pillar trim, remove the 4 HVAC grilles (this is the patience part, they are held in with a small spring tab top and bottom, you need to release the tabs and slide the vents out but be careful not to gouge the dash or snap off the tabs. I use a piece of aluminum roof flashing cut to a thin strip). Remove one 7mm hex head screw from each vent hole (close vents first) pop up dash top and disengage the rear clips. If you use a non-Bose replacement you will likely need to splice some wiring since they have odd connectors. Since its the left speaker I would replace either all three or at least both left and right while you're there.