Thanks Guys was just wondering if the difference was very noticable in proformance and in mpg .Always looking to gain in both and knew this would be a great pool of info. Let me know your thoughts after your trip to yellowstone !
Just got back from Yellowstone. I ran premium (89 or 91) the first half of the trip and plus (87) the second. My seat-of-the-pants impression was of "slightly" more power and throttle response using premium, but probably not enough to notice if I wasn't looking for it.
Mileage was actually worse running the premium, 18.2 mpg on the way up versus 19.1 mpg on the way back. But I attribute that to the net gain of 1600 feet in elevation gain from Salt Lake to Mammoth, Yellowstone, and the fact my wife drove the truck up and I drove it back down. She is more of a lead-foot than me.
My conclusion: Running premiun is not worth it to me.