Hi, I want to install 2 12" subs in my sc400. It has the nakamichi 12-disc 7 speaker sound system and the phone if that makes a difference. I was wondering what the easiest way to install the subs would be. Im assuming i need a new amp to power the subs. Is there a way to run the exsisting wires going to the stocksub through an amp and then to the Subs? Thanks