TIM, I think with MEOWYs' example he is talking about the push/pull effect that a pair of reeds would have on each other? As far as the maximum speed that a reed can go, I don't know what that figure is in the case of a COX setup, but at some point it will lose its' timing accuracy way sooner than a rotary valve will. Take the example of a BW side by side with a TD [with a BW liner]. The reed engine has less crank journal area than the TD, which is a huge bonus right there, score a point for the reed setup. Everything else should be equal now except for the induction. Now put on a 5x3 prop that has been cut down to 3.75" and run both engines. Which engine runs out of lung power first? I've had both style engines go on accidental shaft runs and there is no comparison as to which one sounds the scariest.