These new UMS engines are selling well, however I have not seen too many modelers post flight videos yet. I myself have the 7cylinder 160cc engine broke in a bit on my test stand, however I have not had time to hang it on my 1/3 Stearman yet. I posted the video link of a modeler successfully flying a 5-180cc version on a giant scale yak. I did watch a flight in person of an evolution 9-115cc glo fuel version flying a kit built Stearman at a fun fly a few years ago. The new UMS versions are upgraded in many areas, and include a collector ring exhaust pre installed at the factory. There are several videos on YouTube of them running on purchasers test stands, and they run and sound beautiful. Not sure how much more convincing info you need. I suggest you get one, run it, put it in a plane and enjoy! Maybe you will beat us all into the sky with it. ( Make a video). Most of us have many projects going at once. I still have to get custom flying wires produced in Europe to complete my plane.