From what I've read in many of the forums I think, as JFisher says, its all improvements in throttle response down low, stuff that doesn't always show up on a dyno.
If you think about how PowerNow works and take a look at the PowerNow website, it does all seem logical.
Yamaha Moto France will being using PowerNow next year, so I guess they must feel its worthwhile!?
Also, IMO TBM are a bunch of 'cowboys' so I wouldn't believe anything they say, I'm more inclined to believe the people who have tried the mod and actually ridden with it.
