For the record, I had the opportunity to test an EMPI synchrometer against an STE synchrometer and the readings on each were different.

I do not think they are calibrated well. The EMPI read higher at idle.

My cheapo EMPI buries the needle on the 3,000 RPM test. 

I would be surprised if either one, especially the STE, claimed factory calibration. I'm happy getting consistent readings from the STE. So, are you going to take the EMPI to a calibration lab?

This is an FYI just in case people try to set the same flow number at idle for stock cars, there is no accurate way to ensure the number read is correct.

It doesn't matter.  There is no original flowing Datsun engine anywhere in the country after 40+ years.  Its all relative based on the condition of the engine you are working on.

Sort of... that is the reality of what we are adjusting however, if you want to try to get an approximate bench mark at least ; one that many can use, it will be difficult. For example if a procedure states to set the RPM's to 850 at idle and one person's rpm tester was not the same as another's then it would be difficult to achieve the desired result. I would expect a better level of agreement between $50 test instruments with flow numbers on the case. I now have two flow testers my old EMPI and new STE that I will soon compare for bringing a third into the comparison.

Old Japanese saying...  Man with one watch knows what time it is.  Man with two watches never certain.