Have 2004 sierra slt with bose factory system, want to add extra 10" sub under back seat. Is there a plug in conversion for the amp that will connect to the factory wiring under the cup holder in the center counsel? Or what do I need to do to add amp and sub?

 

You will need a dedicated amp to drive your sub.

Also you will need the PAC adapter to add preamp outputs from the back of your factory stereo to give the amp the signal it needs.

I bought a custom box, PAC adapter, and JL 10'' sub and wiring kit from horizon audio, bout 300$ installed, i already had an amp.

 

I have 2 10" under the back seat
Custom box color match carpet... u will need a adapter..and a amp, and amp kit