Harold is right. On my '03 Sante, you have to get the cupholders and plastic piece off first. There are a few small screws that hold the plastic thing. You have to pull the cushion away to see them. After that, you can reach up under the bow and get to the bolts. Then there were about 2 sheet metal style screws on either side on the rear portion of the cushion that you have to get to from the footwell and the observers compartment. It is a pain in the ars to get to and to put back and get the screws back in the same hull. I think there might have been bolts too. I'm curious if you have the sheetmetal screws of if the previous owner of mine did it.
While you have them off, I would put some baffles in there to hold the new ones. You can see on my old thread on PN that shows the baffles and some of the bolts that you have to get to.
What speakers you putting in?
http://planetnautique.com/index.php?name=PNphpBB2&file=viewtopic&t=7874&post days=0&postorder=asc&start=120