I'd like to see some of these "DOT approved" lights. To my knowledge, all PnP HID lights are illegal. Unless, of course, you are referring to the OEM type bulbs like the D2S, D2R, etc, which require projectors, or HID-designed reflector housings.
Even full retros are questionable, though I do seem to recall having this discussion with someone on F150online.If I recall, the legality of retros was kinnda left up to the states.
I vaguely recall something about the bulb you put into a housing has to have the wattage stamped on the base, and it has to match what was OEM.
There are no HID kits that are DOT approved. They are all made by the same factory in China (ALL) and they are all illegal.