Your confusion is justified, because the RcExl ignitions differ: If you have a SINGLE hall sensor (recognizable by a 3-wire connector) the ignition fires when the magnet LEAVES the hall sensor. These ignitions are used for singles and even firing twins
When you have a double hall sensor (recognizable by a 4 wire connector) the ignition fires when the magnet is ARRIVING at the sensor.. Those ignitions are used in odd-firing twins, fourcylinders and all radial ignitions.