How many amps is your stock alt?
I don't know how much I can help, but I'm running one AQ2200D and a 300W Infinity off of a stock 160amp alt, and at most it drops into the high 11's on full tilt, but it stays in the 12s-13s just below max volume. I'm thinking of getting at least an extra batt to help with the dimming though.
So I imagine you'd probably need an extra battery and perhaps a HO alt, I don't know if someone else can chime in or not.