i got a new sport comp tach and took my car for a drive and i still have my stock tach hooked up and the two tachs are off. the autometer says 7,000 rpm while my stock one reads around 7,500. is this normal? i checked the ground and power they are ok and i hooked up the tach wire to the stock wire in the back of the instrument panel.

 

yea stock tachs are off a little as where you have an aftermarket tach its gonna be dead on. i never understood why people need 2 tachs though

 

i just wanted the shift light really and i bought it cheap. thanks for the answer