I used to use the non-tour Pure Storm and liked it a lot but at times, it felt a little underpowered, even with 17 gauge Bi-phase. The 4D 300 has almost the same specs. Both are 98's. Both have 21 mm beam widths. TW has Pure Storm's swing weight at 312 and 4D 300's swing weight at 320. Pure Storm has 16 X 20 string pattern, 4D 300 has 16 X 19. TW has Pure Storm's stiffness index at 62 and 4D 300 at 60 (this differs from other companies who have it at 64). Both rackets are 10.9 oz. strung. TW has the non-tour Pure Storm as "low" powered. Yet, it has the 4D 300 as "low-medium" powered. Why the difference? How are these rackets different and is TW right in that the 4D 300 will provide a little more power than the Pure Storm? Is this because of the 4D braiding? Any insights will help. Thank you.