I went with 2 se 12's.i think i'm gonna go with an re se and wire it down to 1ohm.
http://cgi.ebay.com/RE-AUDIO-SE15-15-CAR-STEREO-SUB-WOOFER-SE15D2-SE-15-D2_W0QQitemZ400036148162QQcmdZViewItemQQptZCar_Sub%20woofers_Enclosures?hash=item400036148162&_trksid=p%203286.c0.m14&_trkparms=72%3A1234|66%3A2|65%3A12|39%%203A1|240%3A1318|301%3A1|293%3A1|294%3A50