We used to call the kick down, the passing gear. I never like to use it, but it did work. Reason was. there was a pause before the dropped gear change, so I would always manually, shift into 2nd or 1st as needed, for a more positive shift. I don't remember why, but I installed a nut and bolt on the slide on the other side of the slide stop, for a better down shift. If I remember correctly, about one inch ahead of the throttle linkage. It also sets the upshift. I could also be set to be in third gear around 20 up to 30-40.