If you want to convert to brushless it is hard to beat the EZRun 4300kV combo. It's cheap, durable, easy to maintain, comes with a programming card and doubled the speed of my EXT2. We clocked it well over 40 with a GPS. The stock Photonspeed 2 motor barely broke 20! I'm still running the stock slipper clutch with no issues. I think that motor/ESC combo is perfectly matched to the evader chassis. Fast but still very drivable.
http://www.hobbypartz.com/ezrun-35a-9t-3650-motor.html