Well still impressed with the 51 after a full weekend of flying with the 11X7 on the nose. When I came in Sunday night I felt like the 51 could handle a 12X6 Master Airscrew K series. If this thing spinns the 12X6 like it does the 11X7 I don't know what I will do. I have had 61s that couldn't spin a 12X6 desent.