My advice? Well, I have a few choices.
1) Two 8" kickers powered by a kicker amp in the 500 watt range.
2) Two Rockford Fosgate 8" powered by something in the 500 range.
or
3) I'm a Pioneer fan, thats all I have so I have to through this choice in... a 12" or 10" Pioneer sub w/ a 250 watt amp (I think) to a 760 watt amp.
Steve