MTX TNP212D2 12-Inch 400-Watt RMS Dual Loaded 1200-Watt Car Subwoofer Enclosure Audio with Sub Box, Mono Block Amplifier, and 8 Gauge Amplifier Amp Complete Wiring Installation Kit
Why you should get a Car Subwoofer - Sonic Electronix Learning Center and Blog
Bass Packages at Crutchfield
Rockford Fosgate 1200-Watt Bass Package Includes R1200-1D amplifier, two P2D2-12 12" subwoofers, and Sound Ordnance B122-125S sealed enclosure at Crutchfield