Go on ebay and search for f250 subwoofer. I bought a custom made box that flows with the curves of the back seat. I forgot who makes it...but Its loaded with 2 10 inch MTX subs and it sounds pretty decent for a $250 dollar set up. I matched it with a kicker amp, but that amp kept going into protection mode so I swapped it for a Crunch amp, which I've already had in a different vehicle. Overall it sounds pretty darn good!