The Webra "Speed" series are fine, powerful engines. They like to rev and like small props. If the specs say 17.5k, I don't doubt it at all. I have a Speed .32 that turns a 10-4 APC at 15.3k. The Dynamix carb can by picky to adjust, but it's what helps give the engine its power. The C (chrome) part of the ABC is extremely hard and the engine definitely needs break in time. Don't run it slobbering rich during this, but in a only SLIGHTLY lean two cycle. These engines are carefully built with tight tolerances and will last you a long time if properly taken care of. Use a castor/synthetic oil blend fuel like Morgan's Omega. The Speed engines like nitro, too, so even up to 25% is ok although they run just fine on 10%-15%.