Given the likely specific fuel consumption of the engines, 40 gallons per hour is about 75 percent power. So, lets say the conforming airplane will do 205 at 10,500 feet. Using the speed increase with altitude that is found in most other turbocharged twins, that would equate to a cruise of about 235 knots at FL 250, which will be the airplane's maximum certified ceiling. If the temperature aloft is warm, though, the engines probably wouldn't make 75 percent power at 250. In standard temperature, the engines are said to be able to maintain full 350 horsepower to 17,500 feet. The cabin will be at 8,000 feet at FL 250.