Shaft flex question on callaways

This may be relevant, I don't use Callaway irons, but, when I was fitted for my Mizuno's I had a swing speed fast enough for stiff shafts, but when I tried them they were horrendous, so the fitter put a heavier regular shaft in, which was way better.

So just because your swing speed suggests a stiff shaft, it may not give you the best results. A fitter will go on the numbers, a good fitter will listen to the clients feedback as well.