So was at the PGA Superstore yesterday and there was a used set of irons from Cobra, looked like the original AMP irons Fowler played. Anyway, they had MBS Tour shafts in them. I had hit a AP2 Titleist 7I earlier, and a few drivers/3w's, but wasn't hitting very well overall. Stiff back etc. Anyway, I hit that 7i with the KBS shaft and hit 3 bueatiful shots, high, straight, and long. Thing I noticed about them was they felt heavy. The shafts unfortunately didn't have much on them in the way of specs other than the name and stiffness, but they just felt a lot heavier. Might take one of my old clubs and get one of those and see if I can tell any difference.