Are you sure you're not just referring to the fact that factory-fitted HIDs have to be self-levelling, as opposed to actually what gets tested in an MoT ?
For example, factory-fit HIDs also have to have headlamp washers, but I'm pretty sure that's not an MoT requirement.
Hi,
I have checked with the guy who does my MOT and he days the only check the headlight level and if thats ok at the time of test then it wil pass. The warning light wont fasil it, the only warning light that would fail it would be ABS so im told anyway