i have measurments and post placement for a box but need some advice.

[inferno1985]

ok i have 2 ab xfl 12's and i have the measurments for a box and the port within the box. but i dont know what freq it will be tuned to. need some help hear on figuring out how you know what freq the box is tuned to based on measurments and port placement. and have a question on the port also. this will e my first box ill be making so i want to get it right.

[inferno1985]

well the cubic feet of this box is 4.2 i need a 3 inch wide port, 13in tall and 14 in deep in box. but dont i need to make a l shaped port or does it not matter? because currently this port is just straight back to the back o the box it doesnt turn right or left. i dont know if that matters or not?