One thing which is strange and others have been kicking this about is the jump in figures sometimes quite significantly and then reporting no real difference other than a smoother response etc. Wierd.
Motorvehicles are weird to humans, what we "feel" is entirely different to what machines measure.
I have had ridden bikes where tweaks have produced minimal gains, but the "feel" is much better, the word "crisp" springs to mind.
I have also experienced bigger power gains which can not really be noticed by the famously innacurate "arse dyno", although a 25% increase in power should be very noticeable both the the aforementioned arse, and the rate the numbers on the speedo increase at.
Dyno figures can be rigged, I am not for one moment suggesting Hilltop do this, but an operator can do a number of things that I am aware of, and probably more I am not.
A mate of mine had a bike worked on and got the "promised" results, but then noticed despite it being a consitently cool day the dyno readings for the after run had much hotter conditions showing suggesting someone had frigged the temp so the correction factor would make it appear like they got a better result.
"Flash" runs are another trick, the bike should be measured at "normal" temperature and you will have noticed Geoff doing a run or two before taking a proper reading to get the bike to normal temp. What can be done is a bike allowed too cool quite a bit, the oil will still be warm and thin, but the engine temp relatively cool, a quickly taken run at this point will give a better reading.
I have heard tyre pressures and even weight on seat can affect dyno readings a little and a combination of all the various tricks could probably allow for a fair skew of the real figures.
I know with the Hilltop setup you can see the bike being worked on, and hear the bike being run-up.
What everyone seems to agree on is smoother running and at least some performance gains, maybe modest, but noticeable - and the posted graphs do all tend to show a smoother power curve - this often hides the power gain as the bike loses the sudden take-off as it comes out of a power dip and onto a steep upward sweep - this can make fairly slow bikes feel much faster.
I used to have an RG500, this "felt" far faster than the GPZ900R I replaced it with, but the GPZ was considerably quicker in any comparison - top speed, SS1/4, 0-60 etc. just the way the RG500 came onto pipe made it feel mentally fast.
