Need some help on a design

[Edaniels300]

Hey everyone I am in need of some advice on my box for a 1995 ranger extended cab. I have a 15 inch mojo 615d4, and the current box I have built for it just doesn't seem like it's hitting the notes like it should. I do know I am horribly under powering it with a old school Rockford BD1000. I do know I need at min 3.8 cubic feet. One issue I have is depth, it can only be 13.5 depth and 41 inches long but height I have as much as needed. Ports I am currently running 2 ports one on each side of the woofer and they are 3 inches by 6 inches and I believe 10 inches deep. Any advice would be amazing. Thank you in advance