I will have some OEM headlights that take a D1S bulb. I would like to put in a D2R or D2S bulb. Has anyone any experiance with doing this?
The reason for using the D2R/S bulbs is that I can get them cheaper than the D1S and I already have the balasts for the D2R/S.
Any thoughts appreciated.

it would only make sense to use the D2S.

Gosh.. nobody in this world seems to know anything about D1S... damn it.

I have the same situation as you. Did you get any luck in fitting D2S into D1S??

OK, my D1S headlight finally arrived and I personally tried to put a D2S bulb into that D1S socket in there. It will fit into the socket firmly.

However, need to figure out how to get the clip to mount the bulb securely... obviously the D1S bulb has that ignitor on the back so the clip is expecting a much larger base.

Will post more result later...