Xenon / HID Headlight Conversion?
 

Has any of you done a Xenon / HID headlight conversion on one of these cars?

Have any thoughts/concerns/recommendations/gotchas to report? Preferred system/vendor?

Don't do it.

The glass lenses are not made for xenon projectors. All it will do is scatter the light and be a safety hazard.

Yep.

It can be done correctly, but it requires a projector retrofit. Since you've got a W126, presumably still with USDM headlamp assemblies, projector retrofits are available on the aftermarket, BUT I've yet to see one with a remotely acceptable beam pattern.

And preferrably one with SLS, to prevent glare resulting from soft suspension (vehicle easily pitches its nose up leading to unwanted glare).

Just don't so it. You want fancy headlights, but a modern car. My MINI has projector headlamps that are self leveling and very bright, but they don't blind people because they are aimed properly and have a clear non diffused lense

DDM is the preferred brand with 4300k bulb. Anything higher is just blue garbage and will reduce your visibility. I have level controls setup on mine and theres no glare.

Do you travel with the car to other states? HID bulbs are illegal and enforcement is strict in certain states, a must to research...
You can do it, you need to source lights with projectors and it can be done well, costs close to $500 for everything for a nice kit. It is all up to you to design and manufacture and it requires some talent.
If you are not into making something, buy a set of Hella Micro DE lights, install hid kit and mount them in a tasteful place and enjoy, this way you have regular headlights for legal reasons and extra light as needed. Costs under $250. These lights accept the hid bulbs no problem, infact you can buy them with HID but costs $600ish.

Just because I did mine with amazing results I say go for it. You have to be creative.http://www.peachparts.com/shopforum/tech-help/367383-headlight-upgrade.html

I did not do mine with anything like this but I did do an upgrade and very pleased with it. I used a site called rally lites in susquhanna pa. GOOGLE IT.The end results are just standard color but nice and bright. Change over was easy. Maybe hour per side. U get rid of standard sealed beams and get a new unit something like it and put a bulb in it, and near reflector, fits perfectly. I sort of remember the H3 bulb goes in it. Nothing radical, just nice and bright. Really makes the signs POP. I've never been pulled over. They are not blue, just standard color, BRIGHT WHITE. Best improvement I've done to make care safer to drive at night. Think what it is is just what they use in Europe is all just not DOT approved. When you stop close to something you can see the filaments shake on object you are light up. Now that is bright. You will be happy. Call them up they can assist in selection.

I did not do mine with anything like this but I did do an upgrade and very pleased with it. I used a site called rally lites in susquhanna pa. GOOGLE IT.The end results are just standard color but nice and bright. Change over was easy. Maybe hour per side. U get rid of standard sealed beams and get a new unit something like it and put a bulb in it, and near reflector, fits perfectly. I sort of remember the H3 bulb goes in it. Nothing radical, just nice and bright. Really makes the signs POP. I've never been pulled over. They are not blue, just standard color, BRIGHT WHITE. Best improvement I've done to make care safer to drive at night. Think what it is is just what they use in Europe is all just not DOT approved. When you stop close to something you can see the filaments shake on object you are light up. Now that is bright. You will be happy. Call them up they can assist in selection. I think I paid $100 for both sides.