I just switched to the Kfactor tour90, from the prince NXG MP (ick, i know). I've broken 4 sets of strings in the kfactor in 4 weeks (12-15hrs/wk). I've used sensation, synthgut, synth hybrid, all 16 gauge, I'm now doing sensation in crosses with gosen 16 mains, cause i bought a mini reel of sensation for the hybrid. The previous 4 sets were 57lbs, now i'm dropping to 55. I only have one stick of the kfact, I used a coaches kfactor 95 today and he had luxilon *dunno which string* at 55# and it felt amazing, it had great pop, the strings were more comfortable on my arm and i could get my full swing. I'm playing on clay, my strokes are solid, not a lot of topspin, semi western forehand, one handed backhand with fed's stroke and grip on it. My serve is primarily slice/flat, my topspin is a dependable 2nd, i love backhand slice that cuts through the ball, doesn't pop and sail it in the air. Any help would be great!!!! thanks. -benne.