Alrighty, using those figures (averaged out to 69%):the 4 channel is 67% and the subwoofer channel is 71 % effcient.
14.4V * 80A = 1152W
1152W * 0.69 = 795W
795W / 2 = 397.5W
That's probably going to be about 4x52W + 190W RMS at 4 Ohms.
Out of curiosity, where did you find the efficiency figures?