As the title says, what exactly is a "Mustang" dyno. I remember seeing some ricers say they were dyno'd on a Mustang dyno and were like "since it was on a Mustang dyno I probably make 10 more horsepower than it said."
Mustang is just a different manufacturer of dynamometers. Has nothing to do with our cars (other than being the best), but they do show one briefly at the top of their chassis dyno page at their website.
It puts "real life loads" on your car or something like that. Yeah, you'll get lower numbers on a Mustang dyno than a Dynojet dyno.