I installed my S1 in the left rear hatch, below the CD changer. Picked up I-Bus wire from the Nav unit, and power for the S1 from the CD changer. Then ran 4 conductor "silver satin" flat telephone wire from the hatch up to the right sun visor. This method eliminated having to wire into the dome light, and makes it easier to update the S1, or remove it, in the future.