for steering you want a metal geared servo with hi torque so that you won't strip it. depending on what you are doing with it will determin the specs you'll need. for racing you'll want a fast transit time (less than .13) and high torque (120 oz in or more) for stearing. throttle can be a less spec for speed, but you will need torque for braking. Ace make good servos that have lasted a while at the track I race at. I run Hitec servos (the 59 series, not the 6 series) and have had good success with them. with servos you DO get what you pay for, buy the best you can afford.