What I cant understand is why the manufactures dont include such info..............back home Zeoah engines are distrubuted by a gentleman called Toni Clark.........the engines are blue printed, the annoying inch or so of shaft cut off the back of the motor and then test run. With the engine comes the graphs as mentioned before and also graphs using regular bolt on box mufflers and PROPER full length tuned pipes at a couple of different lengths. Its a great source of info on the engine.
You get rpm numbers on several different props on the various muffler types also...........HARD FACTUAL INFO.
And guess what .........when you run the motor that is exactly what you get!!!!

I bet dollars to dirt........engine manufacturers have this kind of info as they test an engine for release (hopefully).

It doesnt cost anymore for a few extra lines of typing on the sheet of paper!!!