On Mon, 17 Jul 2017 00:07:29 -0000 (UTC), "Danny D."
wrote:

Overall, do those yellowed polycarbonate headlight deoxidizing chemicals or
1600-grit polishing solutions actually work well enough to be
indistinguishable from new?

Danny,

My wife took our cars to Sam's Club Auto Center to have the headlights
restored, last year. Cost ~$30 and has a 5 year warranty. They still
look great. Living in the desert with blowing sand and UV damage.

I didn't have to do any work :-|

Sam's Club Headlight Renewal:

https://www.youtube.com/watch?v=F9RyTa2fVJg