My goal was to keep the truck looking as bone stock as possible for security and because I use my Envoy as my work truck and constantly have a ton of gear in the cargo area. No extra room for a sub box!
I began by framing out the interior of the storage compartment with 2x4s. After it was framed up, a sheet of 3/4" ply (I didn't want to use MDF here because I get this area wet with fishing gear and ice chests from time to time) went over in a dry fit. This ply was cut to match the frame to give storage compartments since I'd be using the factory storage as the sub box. After cutting and final fitting, everything was carpeted and hinged up.
Next came cutting 3/4" MDF the size of the storage hatch for the sub. This was relatively simple using the factory hatch as the template. Once the hole was cut out, everything was carpeted and the sub installed. I haven't bolted this to the truck yet because I want to check a few different sound options before making it permanant.
I followed the "My version of an amp install" sticky for the most part running all the wires and sent everything to the large hatch holding the amp.
So I only lost about 4" of depth in the cargo area and was able to make up for about 100% of the storage area, if not even adding a touch. From the outside it looks bone stock and I didn't lose the ability to carry large items, even with the seats folded down.
Here is the look from the rear window:
I probably should have taken more pictures of the steps, but there was literally nothing complicated. All straight cuts and simple wood work. It's not going to win any awards, but I spent about $20 on all the materials that weren't laying around my shop and did exactly what I was wanting.
