Hi Peter, yes my S4 Aero have a Canbus system. The buzzer takes very little current and has not affected the system. I fitted 2 diodes, one to each rear indicator bulb at the back bringing a wire to the front of the mog. This is connected to the buzzer with a variable pot (20k variable resistor) this can be adjusted depending on the volume you want. The other side of the buzzer is connected to earth, I fitted buzzer and resister into a small plastic box and tucked it away behind the dashboard.
Hope this helps.
