I've loaded the engine down on purpose, basically to see what it will do. I am with you on this...I definitely have found the outside of the envelope. Just because the engine can turn this size prop at high rpm doesn't mean it is "happy" doing so. That's one key reason throttle response has been so non-linear

Unloading the engine to a degree will probably allow it to handle the way Todd originally designed it. Reason why Sport fliers are turning the small props. Engine is certainly happier and responds more linearly. Focus and Temptress are very similar lighter loads so they don't need a whole lot of prop to fly right. Backing off on prop size ma be the right thing to do

Only have 11 runs on the new engine so far and it is coming along nicely. I feel the compression developing the way it should as the surfaces wear in properly. Hoping to get some flight time today. I'll fly the 17x12 today which is practically the same load as the 18.1x10. I don't expect the throttle to behave any differently but do expect the noise to reduce. I have not found the 15 3/4x13 3B so I am back to well known performers like the 17x12 which is an all around great performing prop for Pattern planes