I'm running an IVO IFA medium on a 914 and last summer met with Dorsel to balanced the carbs using the Carb Mate which definitely smothed things out - especially at idle.

Later in the fall, Dorsel brought the Dynavibe to the North East Kitfox Fly-in and we balanced the prop. This resuted in a very noticable improvement across all RPM ranges. As soon as the engine fired, you could tell there was a substantial improvement. One of the advantages of the Dynavibe is that you balance the prop and the spinner at the same time - highly recommended!