I did not on my 7mgte. I just set it to 6cyl and the rpms read fine. There is also a 6cyl alternate setting for other types of 6 cylinder vehicles. I am not sure in what instance you would use this, but that would be my second try if the regular 6cyl did not work. I am 99% sure you wont need the tach adapters. Call MSD tech support, they will know and have been very helpful to me.