He's got some hearing damage from .....well.....Murican'ing.....so he needed clearer sound and lower lows.
So I upgraded his Front and Rear speakers with my Arc Audio XDi series coaxial speakers and did a little bit of sound dampening to make sure everything sounds as good as possible.
Then after that, I added more low-end with our ProBoxRocks 10" 800w subwoofer/box combo.
It fits in very nicely and will hold up for years to come with the protective bedliner coating.