Do you have a car with a trunk, or a hatchback, or what? In a trunk, usually the best way to go is with the subs firing rearward, with the sub box butted against the rear seat. Hatchback either rearward or firing up towards the glass. Truck doesn't really give a lot of options, so those just fire into the rear seat. It always depends on the vehicle though, so experiment and see what you like best.
I have one alpine 10" type R in a ported box, and mine's in the trunk, positioned so if i opened the trunk then i can feel the air coming out of the port. My friend told me the theory behind this position is that when the sub hits, the sound hits off the back of the trunk and comes ino the cab area. While sitting in my seat, my friends opened my trunk while i was listening to it, and i heard all the sound just disappear. think of it this way, you have a water hose and you're spraying it straight out versus spraying it on a wall. Notice how the water richochets everywhere?
agreed, but you can also invest some time to improve.you say you have a mega-large box, so could be your subs are able to play freeair. if so, your sub should be faced between (in the middle) of the back seat facing front (your direction) to get the best sound possible. it's old fashion, but there is no way to produce better sound. but of course only if they are freeair subs and I don't know how that jeep looks inside. I'm sure there are some people in this board who know if that jeep is good for free air