You could use a lower KV motor and a higher voltage pack to get the RPM you want. For instance this 530KV motor: http://www.hobbyking.co.uk/hobbyking...ter_Motor.htmlan 8S battery and this ESC: http://www.hobbyking.co.uk/hobbyking...PM_Sensor.html will get the job done. I prefer to use two 4S packs in series as they are easier to find and easier to charge on two smaller chargers.