its hard to say i have ran 1200 with a small stock alt 4ga wire and no battery and was getin bad voltage issue. i would think u can start with 3000rms then add a few batteries and go from there.
right now I'm running 1500 with the 140a alt, 4 gauge big 3, deka up front with 120 reserve capacity, and 4 gauge to the back and not too much drop, it goes to about 13 volts on long low notes.
reserve capacity and amp hour are two different things. I was talking to nathan at XS power and he told me that the ah doesn't matter when it comes to daily driver, it's all about reserve. My current deka has 120 reserve capacity and i'm gonna do a g31 that has 190.