so i am new to smd but not to car audio. The prob. i am having is obviously i need more db. my current setup is in a 95 f150 ext cab. one aq 3500d and one 18. the box is an external aero port box. sub up, port passenger side. i have used to diferent sized boxes with almost no diference at all. First up was a 4.1 cube tuned to 40hrtz. it did a 146.8 at the headrest at 49hrtz. second i built a big 7 cube box tuned to 40hrtz, it did a 147.0 at 47hrtz. so my question is why is there hardly any diference in spl with such a huge box difference. am i missing something? is this sub and port placement not gettin the most outa my truck?