my buddies also upgraded the stock steering servos.
the stockers worked, but as with many RTR monster trucks a stronger higher torque servo is better.
www.hobbypartz.com has some for $12-$15 that are high torque and metal geared.

you can buy the caldera sc 10e with some spare parts for $195 shipped.

redcat also has some alloy upgrades. alloy shock towers, steering knuckles and hubs. those arent nessesary, but they are nice