Wrong about the stiffness of the 2013 Aeropro Drive GT it is RA 74 and is much stiffer than older version. I have one 2013 that I have been hitting with for a month and a half and it is stiffer.....also this information is located on the cardboard cover that has Nadals and tsongas picture on it. Behind it has the specs for the racquet.
Big Difference between this model and the older Aeropro.
More pop on serve
Groundstrokes land a lot deeper in the court as well as more bite on slices
Reason the racquet is a lot more stiffer. I use full poly strung at 58 pounds.