Hey Walker
My good friend bought a yak from great planes, he has built thousands of planes and he really is so smart and does alot of reading also about the reviews of new airplanes, he went to the field, a tar runway and within 500 feet it blew apart from flutter, it cost him 50 dollars to send it back to them to show them, i do not think they went good for the plane, i have read some where about flutter with them, i wanted to buy one they are very beautiful but i have also read of others having flutter with them as well, i have a ys-160, i gave two 120 os-w/pump and two os-91-w/pump and three 30-os all four strokes and most of them were either a year old and two were very new, i had an os-90 fs on my midget mustang and around corners it lost so much speed i gave them all away and bought all new ys engines and les then half throatle with my ys-110 on the same mustang went fast on a corner then the os went on the straight, i was an os man and they are a great engine and they run great and they also warentee there work very well as so does ys, i never have to wait more then a week or two at the very most, i got alot of use out of them and the friends i gave them to have learned so much about flying with them as they are such a good engine, most were new at flying, i gave one friend a big stick with the os-120 w/pump which i was told not to buy it with the pump well i had no problems and the guy i gave the big stick to is flying the heck out of it and a big stick is a great plane to learn from and he is doing so well and is so happy, good flying walker and it is so nice to meet good people specially in this hobby there are only a few jerks, i guess that most fields have at least one haha