I tried it today, wetsanded the **** out of them and i dont notice a difference at all, and im running Sylvania hyper whites.

 

my lights are yellow as ****. its on the inside instead of the outside. i was going to try to clean them but no point since its inside. my buddy gave me some kind of cleaner and i used it on my moms head lights. it worked pretty good. hers were just turning yellow on the outsides and i cleaned them with a soft cotton rag and then wiped them down with water and dried them off and they seemed to clear up pretty good. i will find out what the stuff is and post it up here.

 

You could try some CLR, might work but our lenses come off if you want to sand the inside too, they will pop off the housing it self and when your done cleaning them just seal them back up with JB weld. Just use a box cutter and cut around the grey rubber lining and just pop it appart gently with a pocket knife or flat head.