Electronic tach accuracy

[Skinner]

I just replaced the electronic tach in my 82 Katana with another from a 1993 GSXR750. I commented that it reads high by 7-800 RPM when checked against a digital tach. I assumed this was because the GSXR tach would've been calibrated to a different scale as compared to the Kat. However, I recently read an article about a 1982 Kat and the author commented that both the speedometer and tachometer read high from the factory. So perhaps my GSXR tach is reading "accurately"?

Can anyone verify the accuracy, of lack thereof, of your electronic tach?