The grounding and the voltage stabilizer actually distribute the
electricity evenly around the car. Meaning if there suddenly any
one of the equpiment (eg, air-con, speaker bass, etc) need a peak
in electricity, the stabilizer supply it without cutting down on
other equipment needs.
Without grounding and the voltage stabilizer, you may see a sudden
dimmer in your lights or speakers.
Another advantage is that you will have clearer & stronger
speaker tone as well as brighter headlights....
It will not affect the warranty of the vehicles. 