Hi Frequency numbers refer to the cycles per minute. This is a measurement of shaft flex, however many people rely on this figure too much, as it is often measured in different ways by many shaft manufacturers, in addition to that, it doesn't take into consideration the manufacturers tolerances, meaning that in one shaft that cpm can be 260 and in the same shaft, same flex, same manufacturer, saying the same thing on the shaft, it can be 255 cpm's or 265 cpm's, this is a whole flex difference between the two same shafts!! In addition to that, cpm's only measure the butt stiffness of the shaft anyhow, many people put too much emphasis on these figures anyhow without understanding them fully. I wouldn't worry bout these figures at this stage, as acceptable tolerances of shaft manufacturers make them somewhat irrelevent. As for heavier shafts affecting ballflight, and backspin, normally this is the case, not necessarily because of the weight as such, its normally more to do with the fact that the heavier equivalent shaft normally has a firmer bend profile than its lighter weight sibling, which lowers the flight and backspin, but please be aware that very often these differences will be nominal. In other words, it will NOT reduce backspin from 3800rpm to 2800rpm. No shaft will do that. A change in the head of the club to a lower spinning head, matched to a well fitting ball, then using a shaft just to tweak those figures will often help more. Think of it, as a whole package, the shaft is only one facet in attaining optimal ball flight. For too long we have been told the shaft is the engine of the club, in my experience its more like the transmission, and is only one part of the fitting process. A good fitter will know this, and adjust all these other components accordingly, to fit your game and swing. I really hope my lengthy reply helps and please feel free to stay in touch to let me know how you are getting on, by means of Team Titleist. Regards Jason