Do you ever get annoyed by oncoming vehicles that have bright headlights shining into your eyes on low beam. If you want to join this group of inconsiderate road users, put HIDs in.
Normal H4 globes have a low beam filament across the globe. Our headlight reflectors focus the low beam downwards onto the road. There is less than 1mm tolerance in the correct placement of this filament.
HID globes have an arc, (as in welding arc), that is 3 - 4mm long. This really bright arc runs along the globe and less than 1mm is in the right place to focus correctly. Half the light is shining up instead of down. Simply put, HID on low beam is a waste of time for you, and it pisses off every other road user. The only way to correct this is to have headlights that are specifically designed for HID globes and focus correctly.
I tried HID lights when I first got my Nav. I have since upgraded to decent h4 globes, and rewired my Hi/low beam on relays similar to spotlight configuration. I was losing about 1.5 volts through the original loom.
Another issue I had was, the blue/white HID made the grey kangaroos match the green trees on the verge. Invest your money in good H4's and use your savings for some kickarse HID driving lights.