Some videos of ST bench tests.
GS40
https://www.youtube.com/watch?v=rA6wKuKzqyw
G500 Quickie with Jett Sport-Jett muffler
https://www.youtube.com/watch?v=K9Bdx791lzM
GS61 ABC Ring
https://www.youtube.com/watch?v=tCavoG7VzKU
Those engines will last for the rest of my model flying career.