I have built my enclosure for 2 12" type-r subs and want to make sure I got the port built right so I don't mess up my subs. The box is about 4.8 cu with port displacement tuned to 34 hz. I used the calculator on carstereo.com and clicked yes on the slot port option. My port is firing up (on the top of the box) and is in the middle using the back wall as one side of the port. Dimensions are 3.5" tall and 17" wide and port length is 14" according to the calculator. Does this look right? How will I know if my subs are in danger of being damaged? What do I listing for?