Next weekend I am taking the M5 to the all the windows tinted. I found a shop, recommended by fellow M5ers in Livermore. I am going with the Forumula One ceramic tint ($375 total) but am trying to decide what % to go with. I am going with 50% up fronts and probably 15% in rear window but not sure about the rear side windows. While I have pretty good night vision, how much differenece does the 15% vs 35% have during nighttime driving?