I have an 06 M35 and I just put an HID kit on for my foglights. I got 6,000. Says its a Hella kit, but its clearly not. I bought them from ebay and I will post the link below. This guy was very easy to deal with. He had very quick shipment and answered all my questions quick. Im not sure which brand is good or not. In my previous car I got a Pilot kit (pilothid.com), but had problems with the ballast going out and I paid over $100 for that one. However, they did replace the ballast for me but I had the extended warranty. They were tough to get in touch with though. I would be careful buying a real cheap kit as Im sure they dont last as long. I liked this one because the ballast was smaller than the others I have seen and that made it real easy to install. The driver side was easy to find a space but the passenger side was a little bit more tight. They look great and really make a difference on the look and you can tell a difference on the road. The 6,000 has a blueish tint to them and I think that is a real good accent to the HID headlights. There are so many brands out there right now and who knows, these could go out in a few months but he says he guarantees them for a year. Only time will tell. Sorry I couldnt be of more help to you, but I just wanted to let you know my experience. Here is the link to the ones on ebay I bought.
http://cgi.ebay.com/ebaymotors...witem=