Another major factor to consider in this 20% or 35% battle, is, different tint manufacturers have different transparency ratings, even though it all may still be called 20%. For example, yes the privacy glass is 28%, and Llumar brands 20% film registers at 28%, that is what an Arizona cop told me, when I got pulled over for it. Now Johnson window films are a little darker, i think the 20% registers at 21%, so these are things to consider. for christs sake, if you go to wal-mart, and look at the "2 1/2% ultra violet limo tint) that is a bunch of crap, it is as dark as the purple 15% that can be had. So you must consider the brand, and whether the film is made up of ink pigments, or the metal stuff that good film has in it, that way it wont turn purple down the road. Good luck finding a good shop, and when you do pick one, ask them what the transparency rating is of their films, whatever one is closer to 28% will be the better match. Good day

Dustin