what to use for tach wire on 05 F-150

I am about to install a Python 1400 remote starter in my 05 F-150. I think I have all the connnections and wire colors figured out exept the Tach sense wire. I figured I would just pick up the tach wire under the dash somewhere as I have done before on other vehicles, but it seems that a lot of people are talking about running a wire into the engine compartment and picking up a coil or injector wire (seems like injector is more prefered). Is this the best way yo do it?? just wondering. If I do use a tach wire under the dash does anyone know what color it is??