How important is it to have both engines running at the exact rpm. Assuming that the linkage is correct and fuel tanks have same length line to engine. Ive seen guys splatted with so much caster oil trying to get both engines running at the same RPM while others just tune to the ear. One pilot goes crazy when the engines run up at a deferent audible pitch. while others seem relaxed and let the engines settle in at a particular throttle setting. Do I need a RPM checker thingee or is the audible tone OK