Ditto on CJ7 Tim's recommendation.
Hella H4 housings (Made in Germany), quality halogen bulbs, relays with THICK copper multi strand cables (8 gauge is better than 10 gauge)) going to the solenoid through a fusible link and a same size cable going to the same ground point on the engine as the battery ground strap. It is all about eliminating voltage drops so you can get close to the charging system voltage with the main beams on. The old switches, small corroded wires and hit or miss approach to grounding through the bodywork all erode the voltage at the lamp. The switches are also vulnerable if they are very old, with age they corrode an struggle with current transmisison.
If your Jeep is wired as per factory the alternator is maintaining the voltage at the solenoid, that is where it senses the system voltage. This is the place you will find maximum voltages.
May seem overkill but the difference electrically between 11.5V (my old setup measured this, not even nominal voltage) and 13.2V is around 40% more light output. You may care to measure your lamp voltage on full beam and then compare it to the voltage at the solenoid and cube up the difference.
Why?
A halogen lamp is a tungsten filament with a mixture of an inert gas and a small amount of a halogen gas. In the halogen-cycle you get redeposits of evaporated tungsten on the filament, increasing its life and maintaining clarity. This means you can operate at a higher temperature because it will not burn, which in turn makes it far brighter and whiter. The increase in light output that you can get from this halogen-cycle is the cube of the voltage. YES< THAT DRAMATIC!!
So running a lamp at 10% higher than the nominal 12 Volts gives a light output that is 33% higher. (1.1x1.1x1.1) -1 = 33%
Couple that with shiny new reflectors that are not rusted with sharp cutoff and well made and it is literally "night and day".
