As I said in my last post, we are not interested in any bigger speed numbers in an open cockpit boat. Actually the motors were dynoed on 91 octane fuel. They have knock sensors that protect the motor in the event of detonation. If the computer senses knock, it will pull out timing and richen the motor. We can't keep transmissions together now, so we don't want to add additional strain with more gears and prop. This is a pleasure boat after all.