I believe I've read that they share a lot of common parts, and perhaps the entire manufacturing process, as those that come out as GMS.47s. If that is indeed the case, these motors are notorius for air leak problems. I've read similar complaints between the GMS and the Tower motor not wanting to shut down and/or leaning out too much during flight. I personally owned the GMS .47 and got sick and tired of fighting it. Gave up and bought ThunderTiger. One of my smarter moves.