In this paper, we study the impact of vehicle design choices on the limits of performance for a class of scramjet-powered hypersonic aircrafts in the presence of saturation nonlinearities. A simple 3-DoF model is used to illustrate the main ideas. Tail controlled hypersonic vehicles are characterized by a non-minimum phase zero, and an unstable mode. These dynamics (along with actuator saturations) limit achievable performance. We consider both plant-centric (i.e. without controller design) and closed loop (with controller design) performance limitations. The impact of various vehicle design parameters (elevator location and size, engine size, nose angles) on achievable performance is examined.