Got mine JP VTZF2 4U5... therefore quickly went to queensway to string it. Saw quite a few of the VTZF2 SP having the same specification therefore could not resist to test it and swing it.. tested a few VTZF2 4U5 at a few shop... conclusion is the same... SP is heavier overall and the swing speed is slower. if the stringer who claim is the same, change its opinion when he test my racket. I also have a NRZP JP 3U5... when i test it with my friends SP version, it seem like mine is lighter... Lighter is not always a good things...but the feel of the racket is really good.. maybe this is why JP is more expensive... I do not have specific equipment to measure.... but the feel is really different.... based in mind the original grip is still "On" when i test it!.