I didnt put a 2-speed on it but I did maximize the air intake/outake with the upgraded dual exhaust and air filter allowing me to reach much higher speeds. At stock it would go in the mid 30s, but after I did this I can reach around 40mph if tuned right.
Once I buy my new nitro car I will be glad to race you. With some hop-ups 70mph shouldnt be to hard to reach. My friend just bought a new tc3 and is putting a novak SS brushless system in it. That should give you good competition also.