12's are the perfect compromise between low bass extension and crispness. the bigger the sub, the lower it can play (in theory) but also sometimes becomes less accurate. a twelve is a great compromise between the musical accuracy of a 10, and the low extension from a 15. I have a single kicker solobaric 12. its perfect for the z because it has a great frequency response and also has great power handling while being VERY accurate. check kicker.com for specs. (i'm not running the L7 square...i'm running the last generation circular series...the d series. ) this is a space saving sub as well which is a plus for the z32.