dual 4 ohm and they will be wired in parallel down to 1 ohm. Oh and is a 1600 watt hifonics brutus amp to much.
I've never ran any RF subs, so I don't know the actual abuse these things can take. If you know what you are doing, I'm sure you can get by with 1600 to the pair. Make your box smaller than normal since your overpowering them by so much. Just remember, if you smell something burning, or your subs getting hot hot, turn the gain down a little.