Hifonics BXi 1606D , Orion HCCA-D2400, Massive Audio P1500.1, Power Acoustik A2400DB, or a Power Acoustik OV1-3000D for a pair of subs that are DVC 4-ohm,800W RMS, 1600W peak each?
Massive or Orion. Both are good, I'd say they're about even quality wise. Just be aware that Massives usually put out a little less than what they claim since they are rated at 14.4 volts. (system voltage rarely holds that high).
Power crapcoustic is... well... crap, and hifonics is a notch above that.