headlight voltage
 

does anyone know the maximum watts or volts the high and low beams can handle with out a wiring harness?

Generally, the operating voltage is from low, 11.5 volts to high, 14.9 volts. If you go above that the lamp life will be shortened considerably. If your voltage regulator is working properly the voltage shouldn't rise above 14.9 volts. I can't tell you exactly how much wattage the wiring harness is rated for, but the lamps should be less then 100 watts.

If it helps, a high beam bulb draws 65W and a low beam bulb draws 55W.

is it the same through out all the generations?

The wiring harness uses the same weight wire in all the generations, except the cars that have factory installed HID lights. In that case they might use a lighter weight wire since this system has less of a current draw.