The big thing with HID kits is that they love as much voltage as you can give them. If the voltage starts getting too low, they will not turn on since the ignitor can not excite the gas properly. Why is this a problem with our trucks? Simple, follow where the wiring has to go to get power from the battery/alternator to the headlights. It passes through tons of wiring, a headlight switch, multifunction stalk, etc. Each of these items drops a certain amount of voltage. Now, add in the fact that the wiring is only really designed to handle 10 amps and you are going to be forcing about 30 amps through it momentarily, this large current pulse causes a larger than normal voltage drop.
The solution is to spend a few extra bucks, get a relay kit that powers the HID directly off of the battery using the properly gauged wiring and then the lights are triggered using the plug from one of the headlight plugs.
Something as simple as a slightly higher resistance (something in the 0.1 ohm range) can lead to major issues. A 0.1 ohm resistance in the wiring somewhere can let to a 3 VDC drop. That is more than enough to make the HIDs not come one. So, in short, spend a little bit extra in the wiring department to get trouble free headlights.