i'd use an autometer over a cheapy tach. why are you on your 4th one? mine went out recently and i sent it in to them for service. they called me within a week and said they fixed it and shipped it right back. i think i paid them $45. when i got it back it was not my old tach. it was a brand new one. the cheapy ones suck, from what i understand, and are not even worth the time of installing them.