puttmad,
I have just the information you are looking for. It is taken from the article below. Doubling the kinetic energy means increasing the clubhead velocity by 1.4. Hence if we start with 90 mph we end up with about 126 mph. This is the precisely the range covered by the study. The increase is not linear as shown since the coefficient of restitution reduces with increasing impact speed. Moreover the aerodynamic forces increase with the square of ball speed.
EXPERIMENTAL DETERMINATION OF THE EFFECTS OF CLUBHEAD SPEED
ON DRIVER LAUNCH CONDITIONS AND THE EFFECTS ON DRIVE DISTANCE
FOR BALLS USED BY THE PGA TOUR
USGA Technical Report RB/cor2006-01
Steven J. Quintavalla, Ph.D.
USGA Research Engineer
April 19, 2006