Ok question 1 : Im planning on building my own box but when they say have 12-16 sq in of port space what does that mean? Which part of the port do you measure to get that figure. 2 : would a T-line be a better choice for 2 BTL 12s with a 2.5cuft box? or a regular L-port?

Having 12-16in^2 of port area is referring to the port area in correlation to the box volume. ie 12in^2 per ft^3.

Measure height * width of the port and divide by cubic feet of the box.

I think you have the definition of t-line mixed up with something else.

If your box is 2.5 ft^3 (for example), 12-16 in^2 of port area per cube is just simple math.

12 x 2.5 = 30

16 x 2.5 = 40

So you should stick with 30-40 in^2 of port area if your box is 2.5 ft^3 after displacement (subs, port area and bracing if any).

would a T-line be a better choice for 2 BTL 12s with a 2.5cuft box? or a regular L-port?

I would stick with a standard ported enclosure to FI specs.

1.75-3 ft^3 after displacements (sub, port area and bracing) per sub will suit your needs perfectly. What amp(s) will power these subs?

1.75-3 ft^3 after displacements (sub, port area and bracing) per sub will suit your needs perfectly. What amp(s) will power these subs?

Probably just gonna stick with the Sundown 4500d, and when you measure the length * width for the port size, what about height?

so if I made a box 16in wide, 16in tall and 24in long, with material being 1in thick. Id need a port the same height as the box and just as long, and 2.5in wide? so the overall width would be 18.5?

1.75-3 ft^3 after displacements (sub, port area and bracing) per sub will suit your needs perfectly. What amp(s) will power these subs?

Probably just gonna stick with the Sundown 4500d, and when you measure the length * width for the port size, what about height?

Height x width

Lenght will give you your tuning frequencey

1.75-3 ft^3 after displacements (sub, port area and bracing) per sub will suit your needs perfectly. What amp(s) will power these subs?

Probably just gonna stick with the Sundown 4500d, and when you measure the length * width for the port size, what about height?

Height x width

Lenght will give you your tuning frequencey

AHH there we go, THATs why I got confused lol so when I figure Ill need the port to be tuned to a certain freq is that the wall inside the box? And thanks for answering my retarded 'n00b' questions, I just wanna learn how to do this all on my own.