Alternator and big stereo help...

I'm currently running four Deka 31 series batteries. I just got my hands on about 100' of 1/0 gauge Knukonceptz OFC wire which I'm gonna use to run to my two Zapco 750.2 amps that are running two WS Pro 485's and also to a Rockford T1500 powering two 12" Rockford subs. I plan on having a lot of wire left over and was wondering if it would benefit my charging system to run that big of a wire off my alternator and to also replace the 4 gauge wire connecting each battery together with the 1/0 gauge wire? My biggest concern is the wires off the alternator. Would I just replace the stock wiring off the alternator with the 1/0 gauge or should I run it additionally to the stock wiring? If I simply replace the stock wiring, do I need to add a fuse anywhere? Is there any possibility of harming anything electronic like the ECM or anything by adding the bigger wire? Thanks for any info.

It will absolutely help you. In car audio there is a mod called, "The Big 3" which is basically getting bigger gauge wires from the battery ground to the chassis, from the block to the battery ground, and from the alternator power to the battery positive.

On a boat it's mainly getting the block grounded to the battery and the battery to the alternator since fiberglass doesn't really conduct electricity well.
You want to have as big and short of ground cables as you can here. Your system is only as powerful as your weakest link.
If you have 0 gauge wires going to your amps, that will mean nothing if your alternator can't keep up with the demand and pump as many amps into your batteries as is coming out. This is assuming of course that your batteries are being fed off the alternator and not just a bank meant for the stereo that gets charged up on land. This is also assuming that your alternator can keep up in the first place.

As for a fuse, it certainly couldn't hurt to put a fuse in line as added protection, but you don't necessarily need one from alternator to battery.

Wires I would upgrade if I were redoing the wiring:
-Ground from block to battery
-Power from alternator to battery
-Power from starter to battery
-All power and grounds in and out of perko switch
-All power and grounds from amps to battery