i have an FI sp4 15 in a 2007 nissan altima and recently i tried moving my box around to fire forward like a sealed off trunk. I put it as close to the cab as i could and put pillows and sheets all around the box stuffing it as well as i could, and it wasnt as loud (sounding) as firing it towards the trunk. i then folded my back seats closed and put my box in the cab on the seats so that it was completely sealed off from the trunk ( i have a small box and plan on getting a bigger better one) i tested it out and it was even quieter, like a lot quieter, it had less pressure on the ears, less airflow and everything. Ive talked to people and they say sealing off the trunk sounds way louder but when i have tried doing the same its not even close. What am i doing wrong?