Took a look inside a JL subwoofer… quite the coil and suspension system.  http://www.jlaudio.ca/home-audio-powered-subwoofers-fathom

JL audio dominates the Car stereo market in terms of driver quality.  The salesman said the best line “We learned a lot from our 12 Volt line of products in designing this home theatre sub”  so from now on, Car audio will be forever “the 12 volt industry”

Dual Spiders to support the super high excursion of the woofer…  simply incredible design