I have done that with planes on Realflight - I have changed the prop diameter and pitch to get a feel for what changes in the performance, and have settled upon a combo for my P-51 (when I finally get around to putting it together - it is an ARF, so shouldn't take much time, just gotta get started!)
You can also alter the wing and engine - Now, as far as gyro types, blade types - I haven't gone that far.