It is installing Larger diameter cables on 3 key spots on your vehicle. I learned how to do this installing car stereo systems some years ago. Guys that have amplifiers that pull a lot of current usually do this trick. I figure that it would also work for us XJ guys that run alot of lights or compressors or any thing that draws extra current from our electrical system.
1st- Your ground from your engine to your frame. Can also put a cable from your Negative post on your battery to your frame as well.
2nd- From your Alternator to your Positive post on your battery. It is best to have an inline fuse on this run of cable, just incase it makes contact with metal and causes a short.
3rd- From your positive on your battery to your Fuse box under the hood. It allows more current to travel through your electrical system.
I used 0 Guage on my Honda Civic when I did it on it. I drive it daily.. I figure 2-4 guage (awg) would work as well.... I had about 4,000 watts of amplifiers running 2 15" subwoofers in a wall..I figure it will work on an XJ as well. Couple the big 3 with a larger output alternator and that should clear up any electrical issues...What do you guys think about THE BIG 3???
I am really surprised more people don't do the HID projector route. No matter how much engineering and money designers dump into a reflector housing it will never be as good as a projector. The beam from a projector is much more crisp, puts the light in places you need it much better and doesn't shoot light where you don't need it. There is a reason that almost all new cars regardless of whether or not they are HID or halogen use projectors rather than reflectors. A projector can shoot a much more even beam than a reflector can and doesn't shoot any light above the cutoff so it doesn't get in the eyes of oncoming traffic.
I just purchased everything I will need from a harness, projectors, HID kit, and new housings to hack up to install the projectors into and so far my total is at $95. I will make sure to post my results when they are completed, but personally I think bixenon projectors are a much better way to go.