I recently managed to get my hands on a bargin priced "Titleist 983K 10.5 degree" driver. Brilliant head, like it a lot, feel, draw bias, power with a boring flight. Problem though is that I'm not sold on the standard Titleist 4560 shaft (Reg flex) that's in it. Thinking of replacing this shaft to make this driver the one to keep for the next seasons. Happy with regular flex, always been measured at Reg flex swing speeds. There seems to be a plethora of good aftermarket driver shafts but what should I be considering? Grafalloy Blue - R-flex play too stiff? Aldila One - not heard any reports? Aldila NV65 - seems popular. Proforce XL or Harmon CB. Any thoughts or other recommendations greatly appreciated. Also need advice on where to get this replacement carried out - not all pro's seem able to get hold of quality replacement shafts or willing to fit them.