Posting this here as well as in the C5 Tech section:

My 2000 coupe is in for major engine, drive train, interior upgrades and I am adding a number of new gauges, and electrical components (switches, relays, etc.). I am also moving the battery to the rear to make room for either a centralized relay panel (11 new relays) or a self contained fuel cell for the nitrous system. I have the components for the relocation of the battery (cables (1ga), battery box) but was also contemplating doing the Big 3 Upgrade. I understand there is differing opinions on the need for this upgrade, but with the addition of all the new switches and corresponding relays, as well as an upgraded stereo system and HID lighting I thought it would be a worthwhile addition. With the battery in the rear, should I run an upgraded positive cable from the alternator to the rear mounted battery or to the positive post in the engine compartment fuse box , which will be fed from the rear mounted battery? Would doing so negate any benefit of the upgraded cable from the alternator?

I would be already using upgraded ground cable from battery to frame in the rear, and would upgrade the frame to engine ground cable as well. Any information would be appreciated as I am admittedly no expert in this area. Thanks in advance.

 

Sounds like you're already doing 2 of the 3 wires, throw in a new one from alt to B+ post in engine compartment and you'll be good