I have recently brightened up the eyes on my E36. After taking out both headlight units I then split them to gain access to both lenses. You have to break off the BMW sealant but its fairly easy just pull it off. Now you can take out both lenses clean them with glass cleaner and then do the same to the reflective mirror. Polish up the exterior glass and then re seal the lenese into the unit with heat resistant silicone sealant. Then just put the two halves of the headlight unit back together and pop them back into the car. You also have to remove and replace the black plastic cover off the top of the radiator the results are outsanding !!