The only Audiobahn amps I see rated at 2400 W are the A2X600HQ and A2300HCT. This is a 1 ohm bridged rating (not very practical). Both models have a recommended fuse size of 160 Amps. As a general rule, you should have at least one battery for every 75 A.
320 / 75 = 4.27
These appear to be class AB amps, so the max RMS power with 160A fuses would be...
160 * 12 * 0.6 = 1152 Watts RMS
A stock alternator is typically rated 60 to 120 Amps, but not much of that is reserve that can be used by the stereo. For a system this large you should have a second high capacity alternator.
At least 4 batteries (plus the existing one).
A second alternator.
Possibly as much as 2300 W RMS if the amps really can use the power available to them.