I posted this a long time ago on another forum

"Turbo Magazine has a great comparison of 6 different dynos. The results of course varied by a significant amount. They used a 350Z as the test car and did it all on the same day. The results where as followed

Dynapack (5500) 249.4hp
DTS 257.6hp
Dynojet 248(dos) 235.8hp
Dynojet 248 (windows) 243.7hp
Clayton VTT 265.7hp
Super Flow (SF1853) 228.9hp

I used the Dynojet (windows) as the reference. Most people use this type of Dyno. Some simple math will let you compare results from different dyno’s.

Dynapack .945
DTS .915
Dynojet (dos) .967
Dynojet (windows) 1.0
Clayton .887
Super Flow 1.03

So if you take my car which dynoed at 185whp on a Dynojet (windows based) then you can deduce that it would make about 195whp (185/.945=195) on a Dynapack dyno. Of course this is just an estimate and even different Dynojets dynos use different software for correction purposes. But at least this gives us a guide."

To bad they didnt do a mustang dyno. I know crate did about 180whp on a windows dynojet and about 130ish on the mustang.