Yeah, figures. I asked them the week prior when setting up my appointment what gear they run the car in on the dyno and told them for this vehicle that I heard on the forums it's fifth gear.
They said they run it in whatever gear is closest to 1:1. I assumed they were going to look it up and use the correct one. When I showed up yesterday, I forgot to ask again, and just remembered to ask after all the dyno runs were complete after I already left.
I appreciate the link. I emailed the shop the information so that they would have it for the next M5 owner, and can see it wasnt just "something I heard".