I use
Meguiar's PlastX on my headlight lenses and rear window. I have also considered this as a headlight protectant:
Headlight Film - Boxster 986:Porsche Parts & Porsche Accessories - Wholesale Porsche Parts & Tequipment
I have no experience with the headlight film, so I cannot state if it is effective or not.
Just sayin'..........
TO