If you put both of those engines on a dyno you'd find out how wrong those hp numbers are. O.S. consistanty under-rates their motors. The .18 was rated by OS for what, 1.2hp? Its actually somewhere closer to 1.6 or 1.7 according to rcca if i remember right. The .12 max isn't a power house, but i ran one for 7 years on my GT and it never ever gave me problems, and always had the power i wanted to have a good time. Anyway the point is don't be stupid and buy your engines based on the manufacturer's hp ratings as they mean nothing. Go by what people's experiences have been with them in r/l.