I had labored to death cleaning my old S14 plastic headllights with several suggestions from the forums, but they still have a visible shade of yellow. Well, I finally got hold of brand spanking new S14 headlight assemblies (had to whack somebody for them though

) , but since they're the same USDM plastic ones I know it will just be a matter of time before they turn ugly yellow too. Does anyone have any suggestions as to how to prevent them from going yellow from the get go. I remember somebody suggesting clearcoating it? Any other ideas?
Thanks!