nope, i disagree, it doesnt tell u info about how many inches the port area needs to be, u can mess that up bad cause every sub suposedly requires different cu inches for port, so just because its tuned properly doesnt mean jack sh it.
^^^ its actually a rule of thumb. 12-16sqin per cubic foot of box volume. the thing with the re calc is that you gotta make the volume larger than the target, you need to account for bracing, woofer disp, and the double baffle, and; if u want to get technical, wire
the first subs i ever had were infinity kappa perfects and they came with specs for a very specific box with a 4" round port. turns out i ended up having port noise because it was something like 12.5 sq" of port for 1.75 cubic foot box. my next box had 75% more port area and no port noise...