Well the R6's "143 BHP" and "17,500 RPM", which Yamaha later changed to "134 BHP" and removed the references entirely to the 17.5k RPM, ended up being 106.5 RWHP and 15.8k RPM's ... I believe it was Cycle World's dyno...not 100% on that, but I remember reading it in a moto mag where they dyno'd all of the 06 600's same dyno same day, all fresh out of the box with one track day and a fresh oil change for break in, the same riders broke in all five bikes same-day on the same race track in the same number of laps. The R6 was behind the Triumph and Kawi in HP (triumph was at 108, Kawi was at 112, Gixxer at 106.4, and the Honda was at 104). All of the manufacturers exagerate their performance claims, but Yamaha has taken it too far the last year or two. I wouldn't put it past Yamaha to claim 170 WHP, but I also wouldn't put it past them to deliver a bike that only produces 155 WHP to their claimed 170.
But in the end, isn't 155 enough? You can have more, but why? *shrug* To each his own.