You'd be surprised, I have a 100 powered Classic Flash that is not that much slower than my buddies, who are running 140's and 160's. People are always surprised that it "only" has a 100 in it. You don't get that much more speed with a bigger engine, it does accelerate faster though. It's no different than cars or bikes. It always takes a huge increase in HP to get very small gains in speed. You won't need to beef it up with a 160
Mike