I bought one of those powerdisc tennis training systems on TW. According to the formula for calculating addition swingweight for positioning and weight added (still somewhere on this board), the disc can add as little as 40 to as much as 70 extra swingweight. I currently have only one of the metal tablets so that should be an extra 50. I stuck it on a Wilson PS 6.0 85 with lead tape already attached for a grand total of 385 calculated SW. Took this to the wall for a 2 sessions of practice hour and a half each, and my consistancy with the weight attached went straight up! Rarely mis-hit a ball, and I loved the extra heft. However, the problem arose when I decided to take off the weight and go back to the meager 335 SW. My consistancy dropped back to its previous levels. Racquet felt like a feather once I took the weight off and thought I would be a bit better. Why is it that I get that much more focus with the extra weight? I swing as fast as I can controllably with or without the weights, and if anything, I should have better timing without the weights attached... odd... any thoughts?