i need some help designing a box i have a 1999 explorer xlt 4 door i am running a 18"btl fully loaded daily on a fusion nv2500 my current box is 19h 24w 33d outside dim. with 2 6" pvc ports 15" long. ports and sub firing at hatch. i want to fire sub up and port back and change to a 30x30x16tall any help on port LxWxH would be grate!also any other input just looking to change up i was told sub up port back would be louder.