This is a well done video. As a dyno owner and operator weather plays a big factor in what I do as a tuner, as well as the elevation where the bike is going to be ridden.
Another key thing Brock said was numbers vary by dyno manufacturers. This is extremely true. The industry standard in the motorcycle world is a dyno jet. Another big factor is dyno maintenance. A well maintained dyno will read consist. We have a mustang dyno, which always reads lower then a dynojet. Dyno jets are an inertial dyno, where as a mustang is loaded. That being said, most mustangs will read 12-15% LOWER then a mustang.
Had a local guy just last week come in with a 05 gsxr 1k with a turbo that another shop just built. He said it made 240hp on 6psi... I was like how? A gen 2 on 4psi will make 230hp on 4 with 340 more cc's. It ended up laying down 211hp with a pretty lean tune.
However I always preach to my customers to not get hung up on the numbers. Yes it's cool for bragging rights, but what really matters is how it feels when you ride it. And for the drag race guys, mph directly correlates with HP. Take it back to the track and see how your mph jumps.
One thing I like on our mustang is it show uncorrected, and then WCF which means weather correction factor. It's interesting to see over the course of a day making pull how far apart those numbers can be. Every once and a great while, in the winter down here in Houston the numbers will be the same.
But like in the screen shot here, because of the humidity, there's almost a 6hp difference. That's not that bad considering sometimes it's as much as 15 on extremely hot and humid days.