You need a H7 Xenon (or HID) kit - there are loads on ebay, but..
1. the cheaper kits supplied from China have been found to be a little unreliable
2. you need to be careful with the length of the bulb unit, some kits have slightly longer glass sections that can foul on the inide of the headlamp unit
3. Some cars throw error messages due to the lower current draw of the HID kits (35W per side cf 55W for a H7 halogen bulb) - thankfully its mainly non UK spec cars that seem to suffer, those fitted with day running headlamps in particular
4. Be careful which temperature you choose - Porsche litronics operate at the 450 mark, 6000 kits are fine, but higher numbers are more purple and the actual light output drops.
Whilst some kits from UK suppliers such as HIDs 4 U can be more expensive you can at least buy something that should work with the car. I have a set i bought 4 years ago - i installed them in my old 986 Boxster, then swapped them into my current 987S. You can just about fit all the wiring and ballast boxes within the rear of the 987 headlamp enclosure, so its all watertight. I took about an hour to install mine, but i had the benefit of the previous install in the 986 to aid.
