I formed the box using fiberglass to the firewall and tank. The sides and front of box are wood. The box is sealed. The box will only use about 4 inches of the trunk floor. I'm securing the amp on floor of trunk, the battery secured in fender well. A false floor will be placed over the amp and tool enclosure. Dropping the tweeter idea. Going to leave the factory speaker for now, change later if don't like sound. Also plan to install rear camera, in the plate holder.