get a phoenix gold xenon 600.1, puts out 600 watts at 1-4 ohms, but they are very underrated, so it will be pushing about 800. also with music, you never see full wattage from your amp due to impedance rise, so it probably wont get close to 800 watts anyways unless you play test tones on it.
EDIT: i just put together in my head that the amp puts out the same wattage at 1-4 ohms, so impedance rise wouldnt affect it, would it?