It depends upon where your octane tolerance is. A high compression engine will benefit from more octane to suppress preignition, a colder plug, and an anti-diesel solenoid that closes the throttle blades completely so the engine can't get any air. Again, the module can't do this. When you turn off the key, the primary side of the ignition goes dead and without any primary current, there can't be a secondary current. To satisfy your curiosity on this, hook up a multimeter to the coil +. You will see your primary current when the engine is running and it will go to zero as soon as you turn off the key. If it doesn't do that, there would have to be a problem in your wiring from the key to the coil. How clean is your combustion chamber? If you suspect it could be carbon deposits lighting off, you might try the water down the carburetor to clean up the chambers.
