had a hiss in 1996 mustang base model v6... changed to kenwood 1000$ flip radio and all grounds.... still hiss.. hours and hours later come to find the mustang had a hidden amp buried in deep back of dash, so when i hooked up new kenwood radio the hiss was still there cause the new radio was still sending the signal to the factory cheap ford amp and then ford amp to the speakers.... man after i removed that amp and now the speakers were receiving power from kenwood finally what a difference sounded amazing a 2x as loud... and no hiss! finally. funny thing is that this amp should of only been in GT models but they said some random 1996s will have it even if its base model also when i removed that amp the wire harness was still the same plug just deeper down, so go ford for keeping the 2 connectors the same...lol