mixed injectors
 

I am looking at adding some larger secondaries, however they are high impedance, I am running low impedance right now (s4) I know i've read before that you can bypass the resistor pack for the secondaries and run mixed impedance. Will MS be able to control mixed impedance injectors ? does the PWM % or time differ for each type?

If you use the resistor pack for the primaries, and bypass it for the secondaries, you can just set everything up as high-impedance. You shouldn't have any problem doing that.