Afterburn will be an percentage based increase to speed, maneuverability, and a (very small) avoidance to damage. Nullfactor field is very similar to the JE Environment shield with the exception that it works along the lines of reconfiguring your reactor, you'll lose a percentage of your maximum for the duration, and get a slightly increased recharge, and the field to protect you is generated. It will grant some nullification towards different environmental effects. Hence the way it was named.