Did some serious searching and couldnt get a good answer. I replaced the factory Fosgate unit with a Pioneer AVIC-U310BT and have gotten everything to work fine. However when I start the truck all the speakers make this loud popping sound and when I turn the truck off they make the same sound but louder. This is the only time that the speakers do this, otherwise they and the unit operate fine. I used the specified Metra wire kit for the Nissans with the premium sound system. I have read on some other sites that I need to use a regulator or a relay because the sound is caused by the factory amps turning off after/before the head unit. My question is does anyone know what the actual fix for this problem is? or the volts of the amp turn on wire put out by the factory RF unit to the factory amp. Thanks for any help.