Yokomo has decided that they should be in the business of servos. They have just released a High Speed and High Torque servo.
from the picture, we can see the black heatsink around the body of the servo. It is definitely designed for the serious racers.
Speed: 0.10 seconds/60 Deg (6V)
Torque: 10kg/cm (6V)
Dimension: 40.5 x 21 x 37mm