We often get the question if retrofitting xenon projectors is allowed in Germany. This is what the Kraftfahrt-Bundesamt in Flensburg says:  
It is impermissable to make changes to an approved lighttechnical device. According to German law any change leads to expiration of the approval of the device resp. to the approval of the vehicle.
Halogen headlights No it's not allowed to retrofit xenon projectors.
Spare parts which have a essential influence on the electrical and optical properties of the headlamp may only be provided by the approval holder resp. in his responsibility.
Xenon headlights No it's not allowed to replace burned and old projectors, with new projectors, which will improve the light output, increasing the safety of the vehicle. Over strict regulation In our opinion this is a good example of over strict regulation. We can understand why they make the rules: to make sure no one is glaring other road users, causing unnecesary danger on the road. However, the result is that if you buy a used € 3000 BMW E46, with heavily burned ZKW projectors for example, the only legal option to restore your dangerously bad xenon light, is to buy a new set of headlights, which will cost € 1500+ at a dealer. We believe this is outrageous and out of proportions, that's why we provide kits to restore your headlights for a fraction of the cost. We want to make it clear that installing these kits on a German car, is officially not allowed, and at your own risk. We have sold hundreds of xenon headlight repair kits to Germany customers. We can tell from experience, that if your car originally has xenon headlights, it is very unlikely that you will get into any problems, since you will have a perfect light output, and it's nearly impossible to tell that there are non original parts installed in your headlight. Do the projectors have an E-mark or ABE? No they don't have an E-mark or ABE. Original projectors also don't have this. This is because the entire headlight is one part with one approval. The parts inside the headlight do not have or need a different approval. Even if they would have an E-mark or ABE, it would still not be relevant, since the Germany law does not allow any changes to be made. 25 Watt retrofit (D8)? Since it's not allowed to make any changes to your headlight.