MarkLawson
RT-S PE#0031
...you install the BRP CB and/or XM radio.  I would not know about the BRP Zumo 660 kit, but would guess it is needed.  The entertainment harness integrates the added components into the audio system through the AM-FM radio unit.  It also connects the rear components to a harness connection by the battery that runs to the front.
If your dealer says you do not need it to install the BRP CB & XM, they're mistaken.
				
			If your dealer says you do not need it to install the BRP CB & XM, they're mistaken.