What are you expecting when install a big sub-woofer on your trunk? For me, I want to hear a deep loud bass with the timing that coherence with the overall music. The bass should penetrate to the music and to the room very well. I personally do not need sub-woofer. But it is different to my friend. He come to me and ask for my help, why don't we build one giant sub-woofer box that not just sound loud, but it will sound much deeper. So let's this project begin.