another way is to remove the lamp housings and sand the original yellowed clear coating off them, right down into the plastic using about a 320 grit, working down to 600 grit. Then re-clear them. I run a bodyshop so I have access to some very good clear for this job, I'd reccommend prepping them and dropping them off at your local bodyshop to have them hit with clear on their next job in the booth, ought to be pretty cheap. I did this with my faded lenses and they look like new, been that way for a year now with no degradation.