I'm not sure if the factory tint is removable or not, I'd just have them go over it. When they did the first tint on my truck the guy ended up matching my fronts to the back and then made the backs darker which isn't what I had asked for so they had to remove it a few days later, but the stock tint was left on. Like KC311 said tint the whole truck, this will also take away the look of two different color appearances from the inside due to the two different styles of tint which I had on my 2010, this way it will be an exact match all the way around....good luck and post some pics, I'll get one up soon taken from the side.