The Cessna is either generating way too much lift, too little drag, too much thrust, or something is seriously wrong!!! The C172 service ceiling is 13,500 ft (4,100 m) and Mt. Everest is 29,029 ft (8848 m)!
Therefore, it is operating at nearly twice it's service ceiling... We should compare the original C172 FDM's ceiling to the bomber's new FDM. Mixture ratio will have a great effect on horse power vs. altitude, so that is another variable to consider.
Nice videos!
Regards,
Uriah