Prop balancer

[Allen Sutphin 705]

I installed the prop balancer and did a mid throttle run up and it did smooth things out  up to 3500 RPM.  Most noticeable was at 1900 idle RPM and it made things smoother. So overall I'd say it was worth the $90 investment. Mine will idle at 1700 but you get gearbox chatter so 1900 seems to be better. (Hirth, not Rotax).