my r33 had the same problem,headlights were a very dull yellow colour, i used a glassylite kit on them and they now look great. Took me about an hour all up but it was worth it. After you have cleaned them up there is a coating that goes on over the top to keep them looking nice and clear for a longer period of time...hopefully i wont have to do it again for a while,also noticed a huge difference when driving at night.