I am thinking of installing a tach. I am more interested in checking my cruising RPM than running through the gears and not hitting the rev limiter so I don't need a large face or shift light.
I am also curious about where you connect the wires.
On the 07 bikes, there is a peg in a connector on the back of the speedo in the plug. I believe it is the #3 position. If you have any problems with the tach reading correctly, then wire it to the ecm plug in the #3 position. The rest should be covered in the instructions.