Torque and speed is not just about the motor, its also to do with which gears you use.
Have a look at the tomy gs-03 gearset .
Blue= Torque and Bril accelertion
Orange= Less Torque, Good Acceleration,good topSpeed
Teal/Greeny=Crap torque, doesnt really accelerate and top speed low---- but with a dual cell it would be really fast.
My verdict with a perfection 3.8 motor
look here
http://www.microsizers.com/speedshop-parts.html