What I'm saying is to sufficiently say that the engines produce different amounts of power require that you not ask around about what RPM's people are getting. There are so many variables to consider like elevation, which gas they're using, oil mixture, etc. Basically what i'm saying is that you have to get 20 engines of each "make" and then mix up a whole bunch of gas for them all. You need to have the same guy tune each, run the same prop, and run the same muffler system. After each engine is set, then you can take tach readings and compare what you get. Oh, and they all need to have about the same run time on each. You do this, and I'll even run the statistics for you to see if they are significantly different. I'm confident that if I switched to a smaller prop I'd get the same RPM as andyt because we have the same basic set up. But andyt is also at a lower altitude. My altitude is going to lower my power rating because I have to lean out the mixture. Less gas and less air equal less power. That's also assuming our engines are both tuned "properly." I may like to run my a little richer because it's still new. Not all of the variables in the equation are equal so equal comparison cannot be made. Asking for people's RPM numbers leaves too much of variation to make an accurate statement.