Just got done installing a Prolumen 35watt HID kit on my '08. It went really smooth and they look sick! I was a little nervous because retro-fits like these can come out really bad and end up blinding on-coming traffic. Luckily the stock projectors handled the light great and the cut off is nice and low. Installation was so simple. It probably took a little more then an hour to get both lights done. If your looking into installing HID's I highly recommend this kit. The guys at www.bavtoys.com were really helpful and competitively priced. Heres the pics
Blue and black wire feed into a wiring harness that plugs into the stock headlight socket. Cut a hole in the headlight cap to fit the harness inside the light housing.
Mounted the ballasts on part of the frame near the light housing using 3M double sided heavy duty tape. The ballasts are very small and fit almost anywhere