That's what I have heard from many and the fact that they make rackets of different models of the same racket for sale in Japan adds to the intriguing discussion. E.g. MP 90 in Japan and MP 99 for overseas. Any ideas?
I dont remember the exact reason that the Muscle power rackets had different numbers in japan, i want to say its some cultural connotation. However, the rackets should play identically. More often than not its the Placebo effect.