Mine was turning just under 9,000 on an APC 17X6 buring Powermaster YS20/20 yielding about 13 lb thrust static. stock muffler and no pump. I've dropped down to 16X8 and added a VP30 pump but haven't checked the rpms. Performance seems good for pattern style flying on a 9.5lb UltraRC Quest 2G. I might try a lighter 17X6; Throttle transition seems a tad slow going up and down.