Best 12"sub for car rattlin bass u can feelHARDn be heard frm pretty far away?Kicker L7,DC Level3,orJLw3v3?

On my Kenwood Excelon 1200m monoblock with a final 2ohm load (1,200watts RMS) Please HELP i want the most possible maximum amount of dbs/bass/spl i can possibly get with a strict budget of $500 for a pair of 12"s in a ported bix im going to build to put in the trunk of my 2002 mazda 626 lx max room i have back there is 17 1/2" depth 38" on length and highest i can possibly go on the height is17 1/2" so can someone else please also send me the external measurements and best internal cubic ft (specify net or gross please) for a box that i can build for the two 12"'s that will give me the absolute best/loudest amount of bass/spl for my setup. Thank u soooo much in advance to whoever takes the time to help me out!