Don't know the meters but they were good ones - the same type that EPA use the data from when they take people to court.
That testing article you linked was done at close range (60 feet) and in 2 positions - to the side and behind where you'd expect the brake to increase the sound level.
We can't compare the results - our testing was at longer distance. The bulk of the test points would have been towards the front and side of the firing line.
