I've tried a few of the restore kits, most help but it ain't like new. from a member here I ordered this stuff. it's pretty crazy. it puts a factory type uv coating on the lights and makes them crystal clear too. I did my new lights before installing them and then put ppf over that. they look perfect right now. it was pre cut ppf for the stock lights and I don't think it fit right. I want to redo that for better coverage but you can't even seen it.
time will tell but I think the other member was right, this stuff might turn out to be really good oem quality.
I practiced on my old stock lights that were really hazed up. Just cleaned up with the spray and then wiped the mix on. it would have been perfect if I did some wet polishing, but I was just testing since I was going to coat the out of the box new ones that didn't need any work.
I don't believe that about to many layers blocking light output, that's just silly. if it's clear it's clear. 6 layers of ppf would block less light than a slightly sun damaged len. anything you can do to prevent that is worth while.
my c6 fog light lenses look horrible, I need to either wet sand, buff and apply this coating badly or just replace them. I removed the lenses and did the retrofit on them because I wasn't worried about damaging them but the light output is great. just since it's a retro fit projector, you gotta remember to flat black the old reflector if you can't remove it, it will glare all over the place if not.