Im an intermediate player, I play with medium stiff rackets. I tried an N90 II a few weeks ago and I couldn't get any power, I was struggling to clear tram to tram. But today I played with a Z Force Original and I was clearing effortlessly, like fast drop shot speed but playing a clear. My smashes were fast, and I love the performance of this racket. It is my next racket to get! How can I get so much power from an extra stiff Yonex but not an extra stiff Li Ning? I have a powerful swing but not enough for an extra stiff shaft? So how can I get so much power from the VTZF but not from the N90II? Please help me??!!