I would vote for MRC, had a couple of cars dynoed there.
Not wanting to boast too much
my current S8 surprised us, for a 14 year old car with 120k miles on the clock it made the factory 355hp on the 4-wheel dyno.
Actually I want to dyno my S8 again soon before I get a new exhaust so I can compare before and after. So I would be interested in a MRC dyno day.