I had heard from more than one source that there is a lot of difference in different makes of dynos, as much as 10-15% for peak #'s

I tend to believe this from the graphs I have seen posted here that were done by trucks with the same mods or no mods at all. I know every truck is different and that temp and humidity are a factor. But what does everyone here think?

 

Most dynos use a correction factor for temperature and other variables. This should make the numbers closer for differnet setups, but its not 100%.

Some dynoes are loaded, like the mustang dyno. It puts the drivetrain under load by adding resistance to the wheels to measure power. Non loaded setups, like the dynojet, don't do this and usually have a higher power number since the vehicle hasn't been put under a strain.