ive noticed in a couple of cars who put those 5" autometer tachs in there car that its always a little diff from thier stock one, like 1500rpms off at 60. someone told me that the stock one is usually not as acurate as the aftermarket ones, can anyone confirm this?

 

sure

 

Stock tachs are highly inaccurate

 

I heard a rumor that stock tachs are purposely made inaccurate so that it is registering more RPMs than the crankshaft is actually spinning to cause you to not beat on your car are hard as you actually think you are.

ie, some kid says "man I just took my car to redline" when he actually never even got to redline.

Just a rumor I heard though, not sure if there is any truth to it.