I had 15% put on my fronts and it looks to match perfect to me. I told them to match the back so they put a meter on it and if i remember right he said the back was 20% put they put 15% on to compensate for more light comming in. I also put a 15% strip on the front windshield.

 

I got 20% on my fronts and factory on my rear I can't really tell the difference

 

I ended up with 15% llumar tint and it matches perfectly..

 

im in canada, we cant leagally tint anything beside or in front of the driver. I went with 35% on the driver and pass. side windows its definately alot lighter than factory but it still looks okay.
I would like 20% but we just get way too many tickets here. it sux.