you should check to see what the tint laws are in your state, if you do 2 layer's it will not pass inspection and you can be ticketed for it. Also, there are films out there that can match the factory tint pretty close. Every manufacturer has films that will match most all cars, different manu's for different cars. There isnt a manu out there that has one film that will match all factory tint on all cars. The darkest you can go that I know of is 35% on front doors but most states it is lighter then 35% like 50% and putting a layer of 70 and 35 will put you past the limit, plus it is going to cost twice as much