I bought this amp refurbed on EBAY for $400- and it wasnt a bad purchase!
This amp does do 3500-3600 rms @ 2ohms - 14.4V, but need 17V to get a full 4000!
It's a power hungry amp, so 2-3 big batts and a 200+ amp alt would be reccommended!
For 3000+ watts, $400-425 isnt too bad!!
Has a bright ass voltage display on the face, which is cool in your trunk, but can be annoying at night if its in the vehicle.
So I will give this amp an 8/10!