2010 C250 HID install, how
You can get 35w for the low beams or 55w if you want brighter. However, if you do fogs, don't put 55w in the fogs.
The cap isn't exactly part of the headlights...I guess. If you mess up, you can just order a new pair of caps. I think I remember someone getting a new pair for like $12? I don't exactly know, but they aren't expensive. Pretty sure the part number is even on the inside of the cap.
If you choose to drill, you'd use the rubber grommet which is supplied with the DDM HID kit. Water shouldn't get in that way, but I'm not so sure about the water issue with filing down the side of the cap.





