Eric I have a few questions for you. I'm tired of looking and searching with no results lol.
Did you by pass the stock amp and just run your new amp from the rca out on your new hu if not what in Zfack did you do?
What did you use to mount your amp to the bulkhead wall? I'm wanting to put my amp there as well but I don't want to hit anything behind it..

My plan-
1 10 inch sub buried in the tire repair area I'm going to pull all that **** out place my sub an box in the space. I had another idea aswell....i did a lot of thinking today. Im tossing around the idea of lining the hole with plastic covering my sub box in plastic placing it in the hole then filling the entire area with great stuff foam let it setup then yank it out remove the plastic and bam a perfectly tight fit for my sub and box and it might help with vibrations as well not sure what to do about a trunk bottom yet.... Might get crazy with some led lights and plexiglas.