Firstly what servo are you running, and how many volts are you putting through the servo? A good high torque servo with 6volts going through it will set you up for the best turning.
Also make sure the servo is giving the steering full travel.
The stock wheels and tyres on the MT2 are quite heavy and going to a lighter tyre will improve turning performance.
You will find under power most trucks will push and not want to turn tight, thats just the laws of physics working.
Different setups will alter steering, just play around with different setups.
Tight turning will require you to back off in the turn and very tight turns to brake and swing the back round.