Sorry, but a two speed is almost impossible in this truck. Also, for a better engine, I highly reccomend the OS .18 CV-RX, and I think many others will agree as well.
http://www2.towerhobbies.com/cgi-bin...&I=LXGGP7&P=ML
Also, try the Nitro evader bx clutch bell and spur gear for faster speeds. Also, does the pull start start the engine, or is it already started and stall?