well vvx is not really a 600w sub, i ran them with 850w each and could take more, look at sky high cable for the 0ga and also use that for your big 3 so a 50ft should be suffcient for that and you can get away with 4ga from back batt to amps, u dont have to buy expensive batt as long as agm and highest AH you could find will work, walmart, sams club sometimes can have some sale on batteries or if you can find a place that refurbished batt