Hifonics = budget & Good Elemental Designs = little more $ & Great Kicker = Great Crossfire VR series = Best(of those listed) but $$$$, they are rated at 12.5 volts while many others are rated at 14.5 volts so they are what you call "underrated". JMO Hope that helps.
I strongly suggest Crossfire VR series. There are amps from 600-way over 4000 watts. The Crossfire VR4000D is 4000watts RMS @2 ohms at 12.5 volts. This amp will kick out the juice at 1 ohm, not to mention even more wattage at 14.5 volts. I would guess it would be well 0ver 5000 watts RMS @ 1 ohm. I know for sure the Crossfire VR1000D is rated at 1000 watts RMS @1 ohm at 12.5 volts and at 1ohm @14.5 volts it is 1352 watts RMS(they all come with "birthsheet" stating tested power). They are very well built as well. JMO
