Your opti driver diagram does not appear to match your injector diagram. You must have altered your kill switch design for the injectors. A fix is in order here to show both the injector connections and ignition coil connections on the opti diagram. It would be good to use a representative symbol for each (injector and primary coil circuit) and include all connections for these two devices. You could also add a test point for setting up the PWM settings on the Nano. 