Originally Posted by Boss330
A video "showing the difference" can easily be manipulated with one car being driven less aggresively. It's a much better proof of power to show time slips or similar documentation (as has been done here allready and will be done tomorrow as well).
If the car is significantly faster down the 1/4 mile than a stock car that's down to power. And, quoted 1/4 mile times for a stock M5 can be compared between several M5's that does the 1/4 mile so it's not possible to get away with a staged comparison.
If you think time slips and software can't be manipulated you're wrong, whether by software (hacking measuring devices like they do to ECUs or even Photoshop) or weather, road and car's conditions (one can even show a wrong car's stats). I can continue but you get the idea.
As I mentioned it's valuable to show both, a video and statistics and the tuning company's promise to expect those is what matters. Showing fake videos and fake stats only damages a reputation so it's in their own interest to make it honest.