I'll bet that one of the reasons they put the antenna outside on the roof is because if it was in the back window near the battery you would get tons more high freq whine especially on AM when the IMA kicks in. Electric motor controllers are notorius for putting out a lot of RF interference. As it is, I hear the whine when the radio volume is turned very low. It's not very loud to my old ears but the XYL always complains. It comes right thru the speakers even with volume control turned way down. I would think that a good quality aftermarket system is much better. However, I can't complain because I only hear in mono...one ear is gonzo anway..