I know this is a late response to the thread but I'll answer in case someone reads it in the future.
Federal law & DOT standards for all motor vehicles require a cut-off of light below a certain height for low beam. You cannot see the cut-off with a standard incandescent bulb but if you ever look at an HID headlight from the factory you'll see a definite cut-off that doesn't allow the light above a certain height, so the light doesn't blind oncoming traffic. Factory HID headlamp assemblies are designed for HID bulbs which are much longer in length and have no filament. The HID bulb is a long tube filled with gas and the system has an ignitor. When power hits the ignitor it sends an electric charge to the HID (high intensity discahrge) bulb which in turn ignites the gas. The bulb glows and more than 300 times the brightness of an incandescent bulb. It has no low or high beam. It only glows one way, bright and omni-directional. The lens is designed to have the cut-off, not the bulb. Vehicles with HID lighting have quad lights. Two outside are for the low beam (also DOT requirement) and a separate high beams on the inside.
Herein lies the problem...
The vehicles that come with incandescent bulbs were designed for that type of bulb. In a dual headlamp set-up, it has two filaments inside the bulb that glows when electricity is applied. One glows and reflects up to create a reflection of light that glows down to the road. The other filament glows and reflects down to bounce the light up and create the "high beam". Because the HID bulb is much longer in length and glows completely with gas, the light reflects up and down with no cut-off. Basically, you have people that install aftermarket HID lights inside of standard housings. They are driving around with low & high beam lighting at the same time, 300% brighter than the housing was designed for. That's for the 35watt HID's, the 55watt HID's are even brighter.
Because it doesn't conform with DOT standards it is an automatic fail.
Anything used in vehicle lighting must be DOT approved or is considered "off road use only". Lights that are DOT APPROVED have a stamp in raised letters that simply read "DOT". The next time you replace your car headlights, look closely at the housings and you'll see it. That's why Kuryakyn lights fail as well, they have no stamp.
Do I agree with it??? That's a different discussion. I hope I cleared this up.
Here are images of the two types so you can see what I'm talking about.
HID - No filament, illuminates with ignited gas.
Incandescent bulb - has one or two filaments that glow. When the light blows, it is the filament that breaks and won't glow anymore. That's why when you bang it sometimes the filament connects and fuses and turns on only until you turn off the light again. The filament will cool and fall apart again.
That was a hellova FIRST POST to the forum. Sorry it was so long.