How Accurate are M Series and Crossfire Tachometers?

[Frostbite]

I have read many posts that seem to question the accuracy of the Cat (M series and Crossfire) tachometers and to a lesser degree, speedometers.

Most of us are clutching our sleds based upon the RPMs we are seeing on our tachometers. I think we all just want to get our sleds as close to perfectly clutched as humanly possible. So........

Has anyone compared the stock tach to one on a dyno or through some other means?

How close to the mark are the tachometers?

Are they typically high or low? How much and which way?

Can they be corrected?

Are the digital gauges any closer than the analog gauges?

 

[Frostbite]

I'm a little surprised that not one person responded to this question.

Surely, someone must know?

 

[RockyMtn.Kris]

Analog not so good. Digital is usually witin 50rpm most of the time but from time to time ive seen as much as 150rpm difference