Dawwwwwww. Well, that rules out a giant sub in the center.My wife had some 4" thick foam left over from a project she was doing, and I cut two circles out of it. It was white though, so I topped them with black second skin closed cell foam I had left over ... so when the rear deck cover is in place, you don't see anything through the speaker grills. The OCF and CCF combo blocks out the noise from my stock fuel pump. When I 1st put everything together, I just left the holes open, and the fuel pump noise was too much. The foam circles did the trick though, since the frequency of the fuel pump is so high.
Yes, the fuel tank is lurking behind that panel ... scroll up and see my post above.
The fuel tank in these cars is located in the trunk.