For my landing and taxi lights I purchased two leading edge landing light kits from Duckworks. A previous entry has the install of the assembly. The kit comes with 55watt halogen lights. I opted to upgrade the system to 35watt HID's which are much more efficient with much more light output per watt. I bought a slim-ballast HID kit off of e-bay. I ordered the kit with H3c (H3 compact) bulbs. I am using the reflector from the duckworks kit so it is important that the correct bulb be used to match the design of the reflector focal length.
The installation is covered in another entry on 11/15/09.
Here is the ballast with the HID bulb installed in the reflector.
HID powered up
35w HID and 55w Halogen side-by-side. The HID is great!
