I have 7427 running $OE bin that started off as a 7.4 truck bin. Under flags there is a setting called "cpi/pfi mode. On a normal tbi bin that is unchecked. Under comments it states that it changes the injector firing from twice per revolution to once. When I set the box and gave it a try with still tbi it ran and drove fine. Can anyone tell me what exactly the setting and unsetting of the box is supposed to do?