Don't think you or the YS will like the 16/4. 16/6 is the way to go and the 17/4 is a real trip. With that one get ready for some stump pulln' torque and the ability to stop in mid air once the throttle is down. 16/6 to a 17/4 is a big leap and takes some getting used to, but will bite right into a hover and makes harriers almost automatic. The YS swings it like a champ. Joe