How to: The Big Three Upgrade

If you are thinking about upgrading your stock car audio system to an aftermarket audio system, then this “How To Perform the Big 3 Upgrade” tutorial is for you!

Your car’s stock wiring system was designed to work with stock electrical load in mind.  Any audio system over 600 watts (1,000+ watts for SUV) installed in a stock environment may cause issues like dimming headlights and voltage drops down the road.  An easy way to protect your investment and improve the performance of your system is to perform “The Big Three Upgrade“ with proper power wires.

So “what is the big 3 upgrade?” you may ask.  The Big Three Upgrade is all about upgrading the following stock wires:

  1. Factory alternator positive wire to the battery positive
  2. Negative battery cable to vehicle ground
  3. Engine ground to chassis
Mike Stiers over at Maxxsonics,  makers of Hifonics amps and subs, filmed a great how to video along with a written review below to help you out:

“The Big Three consists of upgrading three wires under the hood of your vehicle. You can completely replace those three wires (detailed below) or simply add additional wires to existing factory wires. The decision is all yours. The current factory wires are generally 8-gauge or smaller and are not made for the high current demands of an aftermarket audio system. It is recommended that you use a nice, insulated 0 gauge wire so that you only have to do this series of upgraded once.

The first of the Big Three is the positive charging wire from your alternator to your battery positive. This wire must be fused within 12 of the positive battery terminal connections. The fuse value must be equivalent to the maximum amperage your wire can handle, which is based on the size and distance of the wire. If you have an upgraded, high-output alternator, you will remove your factory alternator charge wire altogether and use the replacement described above.

The second upgrade for the Big Three is the engine ground to chassis or in some cases, engine ground to battery negative. This is extremely important because this ground is also what ties the alternator ground through the engine block, to the vehicle chassis. For this step, you want to add your 0 gauge ground to the existing ground. Just clean the area thoroughly and secure the two grounds using the same bolts and locations if possible.

The last upgrade for the Big Three is the ground wire from battery negative to chassis. If you don’t have access to the frame of the vehicle, don’t settle for a piece of sheet metal under the hood, but rather, locate the strut tower, remove a nut from the thread, sand all the paint and debris off, connect the 0 gauge ground using a ring terminal on the thread and tighten the nut down. This strut thread has direct access to the vehicle frame and will provide far less resistance than using sheet metal and relying on spot welds. Leave the factory ground in place and clear any dirt, rust or debris from this connection using sandpaper or a stiff wire brush. As a result of these three steps, you have successfully made huge progress in improving the electrical systems performance, decreased resistance and enhanced the ability to supply power to your aftermarket audio system.”

If you are ready to invest in some quality power wire or amplifier kits head over to where you will find plenty of goodies to choose from at extremely affordable prices.


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  1. 1

    just a little bit – when fusing a wire, you fuse within 12~18″ of the voltage producing item, not the voltage consuming item. so, for example, between a battery and amplifier – the fuse goes within 12~18″ from the battery. for an alternator to battery, between 12~18″ from the alternator. as you said, the fuse should be for the wire load – but it is there to do two things; protect the wire so if there is a surge, a $.50 fuse is replaced and not a $10 or more piece of wire, and so our cars dont catch on fire.


  2. 2

    I have been wanting to do this upgrade, only thing it my alt. doesnt have the power post on it. I have a 89 mustang 5.0 LX and all it has are two harnesses that plug in to it. What can i do ????

  3. 3

    I’ve been looking all over trying to find out how to run the engine to chassis ground. I have a 2012 Dodge Charger. Can you help me correctly identify how I need to do this? Thanks!

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