FSX/FS2004 Spitfire Mk XIV Clipped. The Mk XIV was the most important of the Griffon powered Spitfires, and the only one to see significant wartime service. It used the two-speed two-stage supercharged Griffon 61 or 65, giving 2,050 hp. It had a significantly improved performance at speed and higher altitudes when compared to the earlier Merlin powered Sptfires. Model by A.F. Scrub.