I have flown both in my Thai Angel. The Clarence Lee version and the Twister version, both from MECOA. The Twister engine, IMHO, had a little too much vibration for me. The Lee version is better in the area of vibration, but is extremely sensitive when it comes to venturi's and NVA's. I changed the OEM out to a ST NVA and Jim Lee Venturi. Both versions are not hurting for power. I also did away with the OEM muffler and went with a Randy Smith Muffler. Most of my engine runs have been consistent, but I have had symptoms of "surging." Over all both are well built engines and seem to be getting better the more they are run in.
Norm