Besides investing a $hitload in dynamat, what can I do about the friggin engine noise I am getting from my amp? I have heard that if you use a common ground with the radio, it should eliminate it, but I thought that the antenna was the radio ground?! I have the amp under the passenger seat grounded to a seat mount bolt, and the ground wire is less than 6", just like the manual said. If I do ground it with the radio, It would be more like 6 feet. What do I do???