Here in Alaska the highest octane rating is 90 for premium. If you have a vehicle that requires 91 or higher you'd have to do some math and add an octane booster after each fill up.what is the highest octane you have over there in the US? by the sounds of it its only 91, here in oz thats our regular and our premium is 98 and they even sell 101 in a few places but thats very rare!
Regular is still 87 though, so I don't have to worry about that in my 6R.