I play in a local badminton club in San Diego. I bought a new racquet - Yonex Voltric Z-Force. My stringer told me that for extra-stiff racquets i should use repulsive strings like Nanogy 98 or BG66 Ultimax. I have been using BG65Ti for almost 2 years and i am quite comfortable with it. I am open to trying a new string but would like to get expert opinion from badminton central members before trying it. Can someone explain how is the stiffness of the racquet shaft related to the repulsive nature of the string ? If my stringers logic is correct, then what kind of string should one use for a racquet with stiff rating of medium or flex ? One of the competitive players in my club suggested i should try BG-80. I tried a Voltric 80 racquet strung with BG-80 and the string felt like a brick wall. Could this be a bad stringer job or is it just that string is not suitable for me ?