take the seat belt off the top trim off .. one screw and a 9mm bolt.. i think . then re move bottom seat to 10 mm nuts. and undo leather around buckles then take bottom out.. then remove back of seat torxs an the bottom then lift up the remove speaker cover panel with 2 more torxs ( really look for them then when it is loose take it off carefully it has a guide as well .. dont brake it.. then you will see the rear speakers .

 

In order to get to the covers, you have to remove the top trim piece.

Fully lower convertible top.
Remove seat belt upper anchor.
Remove seat belt upper anchor bolt cover.
Remove seat belt upper anchor bolt.
Remove seat belt anchor and spacer.
Remove rear quarter capping.
Remove fastener securing rear quarter capping to ´B´ post extension.Slacken and remove three screws securing the capping.
Lift rear quarter capping and remove from vehicle.

then you can slide your hand down to pry back the flaps of the cover. They just bend side to side, but are pretty stout.