A fuel cell stack needs its subsystems such as oxygen and hydrogen management, water management, heat management and security and control systems to deliver its nominal power. In this paper an optimal combination of these systems for transportation application with maximizing the net output power approach is proposed. The second approach is the maximizing the net output power by optimizing the system parameters like nominal current density and working pressure. The optimum point of this system is located at 172 Amp current and 2.38 bar working pressure.