check with joel (soundxtreme). Hes the person to see for car audio. or view his store at
www.deafaudio.com
if it was me, and your not looking for earth shattering bass. I'll say go with a single 12, and a 500 watt class d amp.
The new fusion subs are good and priced awesome. check out his store. I just got 2 12"fusion subs for a buddy of mine through him.