no walls...just a trunk setup...giving my measurements I think sub up port back might be best. Looking for recommendations, design..what ever help I can get. I have sketch up and Torres,just don't have them down enough to design anything just yet. He didnt mean wall your vehicle, trunk wall is another way of saying sealed off and firing forward.If you can loose some depth and add 1.5" of height you can do forward firing with everything sealed off. lol...I knew what he meant...I'll still be using my rear seat as I have two kids.