Jester, I agree with you in part that there are some engines in which the A-3 might not be the best for. I will follow your advice and add a sentence to stress looking up the manufacture's recommendation. But I think as a general statement, most beginners are probably starting out with an entry level O.S. , Magnum, Thunder Tiger, etc. and in my experience, those engines are easier to tune with an A-3 and 10% to 15% nitro. It is just my opinon though.