I had one about 5 years ago. I ran a GMS2000-47 on it. I never had a problem with flutter at the tail feathers...but I DID decide to epoxy the entire tail section after the nuts underneath coming loose multiple times. Jeffie is right. Mine ran plenty fast using the .47. And I did end up replacing the landing gear...but part of that was due to my poor landing skills. I have to be honest. Other than that .....it's a kick ass plane!