BIG 3 kit includes heavy duty cables that replace your vehicle’s battery ground to chassis wire, the chassis to engine black wire, and the alternator charge output wire. If your aftermarket audio system is putting a strain on the rest of your car’s electronic, you might want to upgrade your factory wiring. This “BIG 3” electrical upgrade package will boost your electrical system’s performance by allowing the maximum current to flow easily from your alternator, greatly improving the system’s ground connection to your vehicle’s chassis.