If you would like more information on torque speed curves and how they can help you choose the best motor for your project then please see What is a torque/speed curve and how does it affect what I need?
If you need to go above this speed but still require intelligent control of the motor you should consider a brushless DC motor and controller (brushless ESC).
Stepper motors have decreasing torque as the speed increases
A point which is often overlooked is the fact that the available torque from a stepper motor decreases significantly as the speed increases. This often means that in applications where the motor is under a certain load (which it obviously has to be as it is driving something) the max speed will be inherently reduced by the amount of load on the motor.
This is why it is so important to understand the load that you need to place on the motor when choosing a motor.