I can personally recommend Hitec servos.

I run an HS645MG ultra torque metal gear steering servo and a HS525BB High speed throttle servo.

High torque for steering increases speed and response, and at high vehicle speed it has the power to turn the wheels unlike RTR servos.

The reason i picked a high speed throttle servo, was not only to have snappier throttle response, but to have quicker WOT to brake times, and vice versa. This is particularly handy for controlling jumps, as airtime is limited.