I can only quote the measurements I have no insight how the measurement-machines are calibrated..

I do agree that 250 BHP should be giving you actually all you want.
They said I was close to 270 but I just drove the thing and it was fast enough, I do not bother to check it independantly for 100 euro's and come to the conclusion that I may have a very fast 250.....
That is 40-45 with an easy DOB....unless you are a freak (positive) and want to go all the way I reckon another extra 40-50 BHP on top of that is far more apealing than discussing a 10 BHP difference....for them there is a stage 2 and 3 and 4 and.......450 BHP is the most they can get out of it...... after that the poor car is breaking down..

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Mind you a fuel difference oct 98 instead of oct 95 can give you the 10 BHP (again measured)...