I would think on a 125hp you would need to be running about a 21 or at best a 23. Sure would think that a 26 was way too much prop for a 125hp. My boat is a Skeeter 18'5" with a 150hp and I am running a 23 pitch ss 3 blade. I know several guys that have 200hp motors that run 25-27 pitch props. What kind of rpm's are you getting at top end? I'm not an expert though, just talking from experience.