I'd shoot for transfer slots at square, idle screws out at 1.5 and the secondary butterflys adjusted to give you an acceptable idle, then mess with the idle screws but you must have enough adjustment in or out to have them be effective. You can adjust the primary idle screw but you are altering the transfer slot that you spent all that time trying to set. The 'holes drilled in the blades' does the same that the secondary throttle stop. does.