Does the OS 55AX benefit from a tuned pipe? I thought that engine was timed for big props but not necessarily high RPM's.
Also, would the 55AX be a good match for the Great Planes Dirty Birdy ARF? I have retracts and an OS 61FX on it but the engine is so heavy that I had to add extra lead weight to the tail. The weight is around 7 lbs, I believe. I will have to re-check that however.