The most obvious difference the hyper voltage ground wires and stabilizer do is make the headlights brighter, improves stereo sound, gas mileage, p/w windows, and improve the cars ignition systems by allowing the car to accelerate quicker with less parasitic loss.

Hmm if changing the O2 sensors clears that code 4 you, I'll buy some myself. I do suspect my car is not running at it's full potential as the engine runs slightly hotter than it used to prior to the check engine light.

Tomorrow I'm buying a 160 degree Jackson Racing Thermostat to cool the engine a bit. It's a $10 upgrade.