I have an Aymar-Demuth 68" D X 78" P prop on my 6 with an O-360. It's flys great and is very smooth. She revs to 2400 on the ground static. She'll red line at full throttle at 2500 feet, 2700 RPM at 203 MPH or so indicated. I tried climbing to 7700 ft where supposidly full throttle will give you 75% power. I went full throttle, leaned out and she still red lines right around 2700, mabye 2725 RPM. Is that what's supposed to happen? I somehow thought she would be running around 2400 RPM at altitude. How can I cruise at altitude 75% power if it revs that high? Do I need more prop? Or am I going about this the wrong way.