Okay I wanted to add a sub and amp to my 05 X5 with no DSP, or Nav. I was reading the threads of people who have tapped into their DSP systems. I am planning to pick up a sub with a built in amp, yes i know that a seperate custom box would sound better. Would the best way to hook up my powered sub my getting the signals and on/off signal from the deck in the fromt dash, or is their somewhere in the cargo area were the stock sub would have gone that I can tap into?