So I am having the same problem w/ PIAA h4 hi/low HID kit....I sanded down the metal under the 4 grounds wires, new battery, replaced the engine grounds, installed a different head unit and relocated to the cup holder. Thought the old Gathers tape player was the cause, music sounds way better now with my carrozzeria. I get interference while the headlight are on and its worse while the lights are warming up and also when the mirrors are folding and unfolding as well. If i put the antenna all the up i get no interference, but its ugly. Autobachs had a pivot SparkEarth on the super clearance rack so I figured why not....it fixed a different issue of one of HIDs not turning on when I turn off the headlights and back on....like at a stop light, now they turn on every time.....so my chassis grounding is good.