Ifin ya wipe the dirt off the chassis of the limo the por 15 is plenty shiny. UV light causes it to get dull but doesn't affect the the protection. Not much of an issue on the underneath side. Unless you do a lot of car shows with mirrors to show off the por 15
i used por and it chipped off after awhile and started flaking. I started using the valspar tractor paint from tractor supply. Its ALOT cheaper also and they got 15 different colors.