I will be doing this quite soon with a piece of 4 guage wire, and I am wondering what size fuse I should put on it. I am thinking of putting a fuse equivalent to the highest possible flow of the alternator (either 100 or 110 amps). Have you noticed major improvements in current flow to your audio systems? So far I have grounded the alternator with a piece of 4 guage and grounded the battery with 0/2 welding cable and still have not noticed much improvement, though my battery is near dead.

 

fuse equivalent (close) to the highest possible flow of the WIRE.

if your battery is near dead then get a new optima.