I have an ‘09 GMC Sierra w/Onstar and right now I have an PAC-OS4. The one thing I don't like about this is I lost my backup sensor low sound. When I back up the sensors starts to beep. When I get closer and I should stop the beep gets low sounding or deep. Since I installed the PAC I lost that low sound. I have had this for a few years and it has always gotten on my nervous. I was wondering if any GMC owners have installed the GMOS-100 and how good it works. I was told by a Metra tech that this retains the chimes and it sounds through the driver side door speaker. Is it worth making the cha