I'm interested in picking up a 913 D2 driver but find it tough to decide on the right shaft based on the results of hitting in a simulator.  My driver swing speed is in the range of 94-99 mph so I usually fall right in between the R and S flex options.  I like a shaft with a firm, but not stiff or boardy feel - firmer tip and medium to med/high kick point.  Shafts that have worked well for me in the past are the NV65 R flex (tipped) and the Axivcore Red Series 69 R flex (not tipped).  I'm willing to trade off some distance for additional control and accuracy, but want to make sure the shaft doesn't end up feeling too firm later in a round, when I'm getting tired or a bit lazy.  Which of the stock shafts in the 913 do you think would work best for me?  I often find the S flex too stiff but then I give up some accuracy with the R flex - should I consider tipping the R in the shaft you think might work for me?  Thanks.