If i run ground wire through my firewall cant i just run power wire from the battery posisitive terminal to the alternators positive post and acomplish the same thing????
why are you running ground wire through the firewall?? second battery, dedicated ground??
running a wire from the battery positive post to the alternator positive post provides a path for the alternator's power to charge the battery. upgrading this wire is just 1 part of the "big 3" but has nothing to do with grounding.