wire size for high amp alternator

Thanks for replying guys. I forgot to mention all of the info on my car. I'm running two electric fans, two fuel pumps ( one full time, another only for N2O) This car has NEVER had a good charging system. The deal with running a ground to the trunk was mentioned ...somewhere.haha...stating that the body is a poor ground when running the amps we run and the distance to the trunk mounted battery.
I was thinking about rewiring the whole car. Have any of yall had any experiences with the EZwiring universal kits? They're about $125.