Rotor phasing comes into play if you are running a crank trigger or when you are using timing retards as in a nitrous engine. If you are running 36 degrees of initial timing, and retarding 16 degrees when nitrous is activated then you want your rotor phases so that it is optimum @ 20 degrees instead of @ 36, if not when your retard is activated you can have crossfire, which is not good with nitrous :roll: