i've noticed my tachometer is unusually higher than the built in tach..
it is 200rpm higher than the actual, which gives me a false result from my shft light during gear shifting, what could be done? my tach is a monster autometer. i had an old one which is accurate before i changed it with the current tach.

 

where did you get it from? Sometimes universal ebay tachs go bad after a while.

 

Did you hook it up to the same spot?

 

you might have a wiring issue...or your tach needs to be calibrated?? these reasons could be the main cause for your issues...however you know your car just listen to engine and shift

NOTE i am not trying tobe mean or rude ...if thats how it came off sorry.

 

factory tachs in the clusters are off approximately 200 rpm from the factory (i believe)

 

listening to it is probably diffcult, i want to squeeze all the output i can get before shifting..

 

the tach signal itself might be messed up, depending on where you have it wired. Is it wired to the spare tach signal in the engine bay? Mine is and the signal on it is all messed up, you might be expereiencing something similar.