I just got a new car and the stock cd player area is so large if I put an aftermarket in it, it'll look dumb. So, I want to put a 10-12" Subwoofer in my trunk with an amp. But, my cd player has some settings I can play with but not a subwoofer out. The question is, the part I want is it a Crossover or Equalizer so i can fine tune my speakers. My car is an 05 Mustang. I would like to keep the stock look but also manage my subwoofer system. Thanks!

-Ant.