I was a professional installer once, this is the best subwoofer made. A 12″ only takes .88 cubic feet for a sealed box, the least amount of space of any woofer made, and you will get twice the bass.
Kicker Solo-Baric L7S subwoofers are the world’s first square subwoofers and are patented. They are known around the world for their unsurpassed bass delivery. The square design help the Solo-Baric subwoofers supply the extra power needed for rich deep bass in vehicle stereo systems. The cutting edge square subwoofer design provides more cone area and air displacement than conventionally shaped speakers, thus delivering more boom inducing decibels. The Solo-Baric L7S provides high durability due to it’s double stitched surround which helps to hold it’s large motors in place. They are available in sizes from 8 to 15 inches, include ribbon tinsel leads, dual voice coils and high temperature copper windings. These subwoofers are definitely made to last and perform throughout their life. Combined with an advanced injection-molded cone and a Santoprene surround, Kicker L7S subs are engineered for reliable performance and some of the most accurate response in the industry.
Take a look at the Kicker KXA400.2