So, as I recall, you are running the 2/0 to the second battery. Then from the battery/ run 1/0 or 2/0 if you have it to spare, that section is so short it won't really matter) to that 8 post unit, linking the initial input on the outer 3 on either side, 3 for the ground and 3 for the positive with 3 hole buss bar links or plates you could make out of copper or aluminum on the input side then through the fuses to the 3 +/- on the HCCA and leaving the two in the middle for the 4 gauge runs to the two Massive amplifiers.This seems to me to the least complicated and the least expensive way to to run it. Remind m