when u replace all the old wire can u just leave it there or even just leave it still connected. what i meen is say there is already a 4 gauge grounded wire from the battery, but you want to use 0 gauge wire. can you just leave the older wire still connected to the battery and grounded or do u have to remove the old wie and replace it. if so wil the 0 gauge now take priority of the 4 gauge?