Re: Aftermarket Sub
The reason you want to use the front door speakers is that they are crossed over in the OEM cabin amp to 90Hz, max.
This is where the system gets is bass imaging, whether Kicker, or BA.
The rears are filtered to 120Hz.
With the rears as your signal source, you can get a "muddy" bass signal. The front doors are a better bet.
If you want a direct subwoofer output from the amp, you can try connecting to pins 5+ and 13-. These are: GY/BN & DG/BN for all but the SRT8 model. On the SRT, you will want pins 4+ & 5-. These are: DG/YL & GY/TN.
Hook to these wires with a volt meter. With the radio on and the voltmeter set at DC volts, you should get a 6 volt output, from either of these pairs of wires, depending on your trim level. If you get 6 volts (+/- .5 volts), then you are getting a bass signal from the amp and you can use those wires for a clean bass signal.
Hope this helps.