Will I regret change to 3.55s from 2.76s

Um.. more like a buck a gallon. $20-ish per tank. If you drive 1000-2000 a year that's one thing. But up that to 10000 miles or more a year and I'm no, I ain't buying premium.
interesting. out by me the difference between regular and premium is only 30~40 cents

well, you know what they say: pay to play. and it is what it is.