Re check all the wires and make sure you have a good connection. But like the guy above me said its probably something not getting enough juice. Take it to a stereo shop and have them check your amps. The local guy I buy from checks mine for free.
1999 V6 Mustang Dark Satin Green , SR CAI, BBK 65mm Throttle Body, Screaming Demon Coil Pack, SR Lowering Springs, Pioneer Stereo, 2 12' inch subs and 1600watt amp, Green Calipers,