"What about the law, what does it have to say on the matter? In virtually every first-world country, HID "retrofits" into halogen headlamps are illegal. They're illegal clear across Europe and in all of the many countries that use European ECE headlight regulations. They're illegal in the US and Canada. Some people dismiss this because North American regulations, in particular, are written in such a manner as to reject a great many genuinely good headlamps. Nevertheless, on the particular count of HID "retrofits" into halogen headlamps, the world's regulators and engineers all say DON'T!
The only safe and legitimate HID retrofit is one that replaces the entire headlamp—that is lens, reflector, bulb...the whole system—with optics designed for HID usage." Daniel Stern Lighting Consultancy and Supply
ALL HIDS are ILLEGAL
ALL projector Retrofits are illegal
All Aftermarket headlights modifications that involves opening up the headlights are illegal.
Once the headlight is opened up, it has to be re=approved by the DOT to be road legal. even if its professionally retrofitted. Check any retrofitters website, and it will say for "show use/ off-road use only"