I found that Plexus works well on my flip up windshield + full face auto tint helmet shield ,helmet etc.
My bud had to cut a custom windshield from (non hard coated poly) for his Can am Mav because he changed the roll cage.
I noticed how bad it got, scratched ,yellowish, looked like he was washing with steel wool and comet!, yeah it was bad....
Plexus brought it back 90%+ filled most of the scratches ,clear!
That was hand buff with a soft rag!