Nobody can tell you much of anything without having hands on, and up close and personal. The best way for you to go is with a tach and a way to measure the airspeed. And a handful of props. The age of your engine, your fuel blend, whether or not your props are in balance, how slick your model is......... etc etc........

And so far, it doesn't appear that you've mentioned what engine your running. What does it tach on the ground now? How are you measuring the speed?