94 mustang gt with the mach 460 in it. clarion head unit, kicker 600.1 amp with l7 10. if the head unit is on i hear a really loud pop noise coming from the speakers when i turn the key to the start position. not sure if its just the sub or all the speakers but ill find that out at some point today. at first i thought it was a bad ground because i would get alternator whine in the speakers at idle and just above. but i cleaned the battery to chassis ground and that went away. plans are to clean all the grounds i can get to and make sure all connections are solid. also going to see how the PO had the system wired in as far as how it turns the amps on (either HU powered or ignition on powered if that makes sense) any other suggestions?