Installed a very simple system. 2 speakers. No amplifiers. Everything works fine until I start the car. Then, it buzzes but, I don't hear it change pitch when I gun it. That's new to me. All the times I've ever had to solve RF Noise issues, the pitch would change along with the RPM. Anyway, I was running 1 shorty spark plug because 1 of my header tubes is too close and that shorty plug was a non-resistor. I swapped it for a shorty that has a resistor but, it availed me nothing. Same noise. I bought a filter and installed it. Same noise, still. Pulled the antenna and tried the AUX plug in. SAME THING! I'm at the end of my wits so, here I am. Thanks in advance.