Big Three Upgrade
 

For those of you who dont know this upgrade replaces or augments three key cables in the electrical system with 1/0 or 4 gauge wires: the battery ground to chassis wire, the chassis to engine block wire, and the alternator plus to battery plus wire. This increases your electrical system's current flow capability, ensuring a more consistent voltage under varying demand conditions.

I am going to be installing a 500 watt amp for a 12"sub soon and I was wondering if anybody's done this upgrade to their Jeep. I also run a cb radio which draws power from the electrical system as well. If you have done this did it help with dimming headlights? or did they even dim at all when you installed a sub-woofer?

Another note/edit: I've been doing a bit more research and have came across the fact that my amp can push up to 650 watts if installed well, i know its better to have a slightly over powered amp but would running 650 watts rms through a sub-woofer designed for 400 watts rms be okay as long as i tuned it and set the gain well?

I did my big 3 upgrade years ago when I had an Alpine type-R @ 1000w RMS. I was planning on adding another so I used all oversized 0/1 gauge and built my own wires using KnuKonceptz wire and a hydraulic crimper. I'm also running a Grand Cherokee 136 amp alternator, rewound to ~160 amps by a local alternator shop which is a great budget upgrade to the factory 90 amp alternator I had.

Meanlemons.com makes custom high quality cables for our XJ's, 4 gauge wire would be more than enough even if you do want to add more electronics

The important thing to note is the factory fusible link (positive alternator to battery wire) needs to be replaced with a fuse (I use AMG MEGA fuses). Additionally to the big 3, you will want to upgrade your battery to fuse box positive wire and consider installing a headlight relay as well for overall efficiency.

Awesome info thank you very much, you just explained almost exactly what I was looking for. Im going to do the big three upgrade and do my headlight harnesses as well. If i ever decide to add a second sub-woofer and another 500 watts ill probably go to a Grand Cherokee alternator for that extra boost.

Hey NEcherokee, I upgraded mine months ago. A forum member Neal Emmons made mine. Great guy to deal with, does GREAT work and the wires are really heavy duty. I also replaced my alternator to a high output alternator just to be safe.
All new speakers (Kicker), fronts with crossover, rear & double 12" bass in the back cargo area. This system, makes the factory system, sound like music coming from a swimming pool (under water), 100% improvement over the factory system.