When i first went to see Matt the rollers down in yeovil were actually run by the main company performance3000, and my car on completely standard parts was about 6% up on torque and bhp... not really possible even for a 'good day'
However since Matt has taken over the remapping side and is the sole user of the rollers they do seem to be a lot mre accurate, backed up from a couple of different sources now..
For example a friend of mine has an old sirrocco which he has fitted a 20v corrado engine into, when we were there just a few weeks ago, Matt did a re-calibration for the file he had saved for the actual car.
I personally do not believe that Matt is the type to BS people with figures, and while i dont know whether he is touching the advance on the 180's, he sure as hell has been with the diesels.
the only problem we have had is that running upgraded (hybrid) turbo running over 22PSI with mild injectors fitted would cause head to lift... He has since worked out how to tweak things better and has taken the advance out again as he did not need it.
There a few diesel drivers who have had to get Matt's remaps turned down because they were too good and induced clutch slip!
Just cos a guy is an independant, does not mean that he does not know his stuff...