My rear windows are the factory privacy glass. They appear to be about as dark as 25% window tint. I would like to put 15% on the front windows. Has anyone used 15% on all of the glass (front and rear) or any other tint? Did the front and rear glass match, as far as color is concerned? I guess GM doesn't do 5% on the rear. Thanks in advance. [REFLIST][/REFLIST]