I got done for this a while ago. Can't remember what the percentage is, but once i removed my tints and had the windows rechecked, my standard focus glass was to within 0.5% of the legal limit. Have a look at the black stamp in the corner of your window and it will say tinted. Pretty much all glass is tinted as standard this way, so you can not put any more film on the front side windows. Anything on the rear side or back windows is ok tho