What is the big three upgrade?
Sorry, I missed this.
The basis is:
-Corrosion is not uncommon in either of the battery wires, which causes various electrical power loss issues.
-The wires are typically the smallest gage (size) wire possible to support the factory configuration. Every wire in the vehicle actually fits this thanks to cost control, but the main power and ground wires tend to be the most affected.
The big three typically refer to the positive wire from the alternator to the battery, from the battery to the starter, and the negative wire from the battery to the engine and/or chassis ground. My memory of the stock ground locations is a touch hazy, but the battery will typically connect to the passenger head and then another wire will run from the engine block to the chassis and from the other head to the body.
Ideally, you would replace the positive and negative wires with larger versions. Welding lead wire is ideal because it is solid copper and and flexible. Some have used amplifier power wire with success, that wire is typically a copper clad aluminum. If you use an adhesive heat shrink tubing, you will pretty much seal the wire and minimize the possibility of future issues due to oxidizing of the wire.
You can go with a larger capacity or higher CCA rated battery, but you are usually limited by space. Sometimes a higher rated alternator is beneficial as is going with a dual battery set up. Neither is really necessary unless you are running a serious sound system, run several "off road" lights, and/or have other high load electrical items.
