I have decided to go with the "Rayban" brand tint the installing shop offers. My original setup was to do the back window -20% tint and the sides -35%. I've been told that in CT side windows must 35% or lighter to be legal. I want them to be dark - My A6 is silver with a black interior.
The big question is in Connecticut State should I go with 20% or 35%.
The 20 in the back will make ure 35 on the sides seem much darker, (especially if you have a dark interior) I would say go for it because, in the event you do get pulled over the only way i've seen the cops check the darkness of the tint is a hand-held machine they put over ure driver-side windows. I can't see them checking ure rears. I attached a pic for you to get a better idea
I plan to do the front and rear doors in 35% and the back windshield at 20%. The only law is that the front windows must be 35% or lighter in CT. back windows and rear doors can be darker than 35% if wanted.