I absolutely love my Ki5 with Maxim Touch 17 at 60lbs and am getting ready to string up my K90 and was wondering what tension would make it feel most like the Ki5. I would guess somewhere around 55. I just strung up my St. Vincent PS85 with Gosen 17 at 58 and do not like it at all. I string on a fixed clamp Wise2086 machine constant pull ON. Prokennex Ki5 100 square inches ~61 stiffness -corrected thanks to "forthegame" Wilson K90 90 square inches ~67 stiffness I am a 4.0 all court player and base most of my likes and dislikes of a string on volleys, half volleys, swinging volleys and overheads. I get along with all strings from the baseline.