I'm running the FRPP TrackKey with the "Track Idle". Ford actually recommends an oil separator with the TrackKey and lopey idle, along with 91 or higher octane to combat any pre-det. If I were to install a supercharger, I'd also want one installed on my car.
For every other user, I'd consider installing a quality oil separator just peace of mind! Can't hurt, right?!
2014 Mustang GT 6-Speed Manual
Major Mods: ProCharger P-1SC-1 Stage II, MGW Race Spec Shifter, Eibach Sportline Springs