I installed hid kit into my original halogen housing.

Most will give you headaches with regards to dash errors. Look for genuine mteh hid kit on eBay, you will need h7 bulb.

I installed mtec h7 hid with NO errors. They are more expensive but you do get what you pay for. The only problem is in the installation itself as the access is really poor and you have to be a contortionist to get behind the headlight, this was the biggest headache for me and took me hours to do!

The result though is very worthwhile.

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2009 135i M Sport Convertible
2008 X5 3.0si
2003 E46 318Ti M Sport Compact - donated to parents
2003 116i Hatchback - donated to brother
2002 316Ti - Sold
2000 318ci M Sport - Sold
1998 318i Sedan - Sold