no need for a gauge, the Elantra already comes with one!
As for the kill switch, no thanks, somehow this Elantra needs it's power steering, tried EOCing and got scared when I needed to turn and change lane on a downhill ... never needed both hands on the steering wheel with a disabled PS on any car but this one!
Though, if I "plan" my EOCing better (like clutch starting the car before curves, etc..) it could be ok!