Like my heading says, I have a 2006 GMC Sierra with the Bose Premium sound system. I have a Z110BT installed, with the software updated with the lastest maps, etc. I have XM radio installed, as well as the traffic tuner. When I first installed the system a few years ago, it was plenty loud. MP3's would play louder than XM, but that was alright. Now, though, I can have the system turned up to the max, and can't hear it with the windows down. Has anyone else experieced this with the Bose system? I took out the head unit and checked all of the wiring. I do have a PAC module hooked up for On Star and the door chimes. Not sure if that module might be the problem. Does anyone have any ideas or suggestions? Thank you in advance!

My 05 Escalade did the same thing. I had to bypass the bose amp to fix the volume issue.