just buy an eclipse sub, make room for it, and call it a day. or memphis.
i have a memphis m-class 10 right now which i like but it doesnt drop as low as i would like it to sometimes but i dont have enough space to accomodate the mounting depth that is required for the m-class 12 so i wanted to go with the slim mount pioneer 12 sub because i can get that mounted behind my seat with no problem and still be able to lean the seat back.
PIONEER SUBS SUCK MY ASS, THE ROCKFORDS SHALLOW SUBS SOUND THE BEST, OUT OF ALL THE SHALLOW SUBS ON THE MARKET, MY SHOP HAS KICKER, ROCKFORD, PIONEER AND KENWOOD. THE ROCKFORD SHALLOW SUBS SOUND THE MOST LIKE A REAL SUBWOOFER SHOULD.
the pioneers are bout the baddest slim line subs out there and they run around $260 and some change a piece but they are well worth it. getting 4 soon for my Titan and using Crossfire amps