Following the successful Mark II Learjet modification program. The Raisbeck Group set out to improve the performance of the Sabreliner series of aircraft. By applying a unique combination of theoretical analysis, flight test development and advanced FAA certification methods, the Raisbeck Mark Five Sabreliner became a reality. This configuration, with advanced aerodynamics, systems and structure has been incorporated on both existing and new production versions of the aircraft. It offers a minimum of 25% range increase while maintaining or reducing takeoff and landing field lengths. The development approach used for the Mark Five system is detailed, including the rationale for each of the improvements incorporated. FAA certification plan procedures used on this program are discussed. Performance improvements realized in actual operation of the Mark Five system are also detailed to demonstrate the advantages from a customer's viewpoint.