Well on my bowtech commander jacked to 71# my bow with the stock brass knock and the rubber button to show the factory knock point brings the bow down to 303FPS and with a kisser it averages 293fps which sucks....so i removed it and took off the factory string silencers and put cat whiskers on cables and string seem to be getting 305FPS...so i dont know if its based on the bow and let off but i know i lost speed with my kisser.