Don't forget the stock graphite!
How can I forget, it's probably what I am going with
I had my set built with the Tour 90's and when I was hitting them side by side with the C-Taper 90, I couldn't tell any real difference in ball flight to my untrained eye. They did remind me of a stepless Tour 90.
It's hard for me to believe that TaylorMade didn't make the Aerotech SteelFibers available to us. Every steel iron shaft on their optional list is available, but, only the stock graphite? Thankfully, there are four lighter steel shafts available. So, maybe one of them will work for me.