check out my setup in the owner gallery, only a single 8" sub, but it sounds really good for what it is, and you keep FULL use of both back jump seats. Let me know if you need some more info on the setup.
Only thing other than my current setup I could come up with is cutting a crawl-through, and loading a few 12's in flush with the back wall of the cab and 95% of the box back in the bed with a tonnaue cover. That's probably what I'll be doing down the road when I have tossed cash at enough other stuff I wanna do first!
I also found a pic of a guy that built a whole new seat bench in the back and sank a couple of 10's and amps/crossovers all into it, with a cushion cover so you could still use the seats if needed. I have the image at work, I'll post it tomorrow, it's a really sweet setup.
i had two infinity 12s perfects in my xcab with a custom built box that was mounted to the rear seats. so the xcab part became useless but thats ok i had boom. but then it got stolen now i have an empty space and no boom.
I lose one of my back seats, the one behind the driver (if I move the box over, takes like 5 seconds). But I scoot my seat all the way back to drive anyway, So its impossible for anyone to sit there in the first place. Plus system can be removed with no problem. I also put 6x9s in the factory locations. More pics of my xtra cab system can be seen in my owner's gallery, but i attached my 6x9 pic. The speaker grill goes on like usual and looks like normal 6 3/4s. Love to see other's pics!
I finally gave in and decided to take out that sheet metal storage area and fiberglass a custom box with some comfortable seats mounted to the top. I'm going the way of 2 10W6's as well as the stealth box w/ a 10W3, the 6X9 replacements look like they fit real nice. I'll post pics when I get 'er done.