I have a 2005 300c. I just installed a new cd player and now trying to add a subwoofer in the trunk. All the wires are hooked up correctly. The ground from the amp is connected to the same ground as the battery. It seemed to work fine when I first installed it but quickly turned out making engine noise or collecting noise from something else. My remote wires and rca plugs are ran from the back to front on the right side of the vehicle. The positive wire from my amp is connected directly to the battery which is a maintenance free battery located in the trunk. Any ideas what the noise could be coming from? or any ideas for improvement of my installation? Thank you!