>> Every penetration needs grommets and strain relief. You mean the grommets and strain relief that are already present for windows/speakers/locks? In most ca

>> Every penetration needs grommets and strain relief. You mean the grommets and strain relief that are already present for windows/speakers/locks? In most cases it's probably not even additional wires as power and control (either can bus or lin bus) are already established from the door to bcm (body control module).