I have heard that SPP makes a 50W HID conversion kit for the S4 but I have been unable to find any such kit. If the item is out of production, does anyone know of any other reliable kits worth checking out?

 

I installed a 50watt HID system in my 2002 TTqR and did a write-up on the system at AW. I get emails all the time about "Where can I find them?"
I dont know anymore. I was one of a very few who got the system at HID4LESS. They are now gone but the ballast company is "Auerswald" out of Germany. Good luck.