Forgive me if this is a stupid question. If I got a set of xenon headlights for my a4, could I use my current hid kit with them. Would the bulbs fit. If not is there a D1S bulbs that will work with my aftermarket ballasts?

The light units I can get cheap enough but don't come with ballasts or bulbs. Do I have to get oem bulbs and ballasts?

What you guys think?