I'm not a big fan of the mirror type tint, so that ones up to you. I do know that the 20% looks pretty damn good. The law is only concerned with the side and front windows, but I also don't much like a noticable difference from the back to front either. Generally speaking I've noticed the cops don't really bother you to much unless your in an area with a lot tuner cars. I guess what I am saying is that I like the 20%, but it's not my ticket if you get one.