i have pioneer 6x8s in the rear with the factory 460 amps and front kicker mids/high speakers running off the pioneer head unit. my problem is with speed and rpm difference my radio in the rear gets gets louder and quieter in lower speed/rpms. is this the factory amps issue or the alternator issue. its rather annoying. if it comes down to it. im going to run a 4 channel amp. anyone have inputs?