At the risk of this thread becoming even more convoluted-Its not really the correction factors, everyone uses the old STP/SAEJ607 and not the newer SAEJ1349 which is how the OEM's rate their products. Dyno's are all over the place more than likely because of other factors like cell construction. Where does the engine receive its intake air from? How is the air circulated/exchanged? Is the air pushed in or pulled out? I know of a dyno facility that doesn't even have any air movement at all, so as the day goes on it just gets hotter and hotter and more contaminated. That definitely effects the numbers. @ UNOH they blow air into the room while my own system blows it out. What does the exhaust system look like? I'm below grade so my exhaust actually travels up and then out about 13' into 6 large mufflers. How restrictive is the system? Is there any weird adapters involved? And so on and so forth. Correction factors can't possibly account for all of that with 100% accuracy, but it actually does a pretty good job. FWIW I think Nick's dyno is spot on and maybe even on the "tight" side. J.Rob