jeep wrangler box size

What is best speaker and box build for my jeep wrangler? I will be pushing it with the JL Audio 500/1 mono amp. Let me add also that I would like to feel the bass and hear it going down the highway with the top off. ?

I have two pioneer premier 12" shallow mount subs. I custom built a downfire box to fit in my 2007 jeep wrangler jk 4 door. (diminsions 32"L by 16"W by 18"H) They sound like they are possibly double hitting and muffled. I believe i may have to much air space but not sure. I would like to rebuild...