I have a 03 Quad Cab and I installed an Infinity BassLink sub. I stood it up on the trans hump between the seats. I didn't need to secure it because it fit so tightly AND, I can easily take it out if I need the room. Plus, I didn't give up the storage space under the rear seats. It has its own amp, too so you don't have to find room for that. Everything else about the stereo is stock and it sounds AWESOME.
Just my $.02.

 

Hemiriden

 

I have one jl audio W3 and it sounds really good! A 10" will sound better then a 12" if you are cutting corners on airspace! You can mount more then one! Just depends on how much you want to spend! Cartoys custom made my box!

 

bring it over. i'll build u a box.