I do have a major question? I seen that someone made reference to PSP, i have read on their site, klausaudio's site and subwoofer-builder.com(think that's the name) and none of these sites allow calculations for the amount of power going to be used!?!? These calculators help determine length but you must give the port area to do it. The problem i'm seeing is when I build an enclosure, I may only have just enough space for an optimal install. To gain NET volume, I have the option of going with flared port(s). Using box modeling software, i am able to see calculated port velocity and calculated port length by giving the software a port area just like with these other calculators.....but there is a difference. Air speed in the port does not flow slower just by increasing port area, or not just by using flared port(s), but also by decreasing output power from subwoofer(s). So... how can these calculators properly give me an appropriate port if i have to guess on the port area without seeing a port velocity graph? I am trying to do some research on if and how much a flared port can reduce port area requirement before you fall below a specified speed of air at a given frequency. For instance, one source says not to exceed 145ft\sec for daily driver or not to exceed 37ft/sec for SPL applications. So, let's say i don't wanna exceed 130ft/sec or i will have audible turbulence(theoretically). This software does NOT take into consideration that flared ports may be able to decrease the required port area based on the outer size of the flange(i guess because it would be too complicated due to angles and such). So, this software tells me for a 2.7 cu ft box NET at 35hz with 3,000w of power before resistance rise, I would need a port area of 41.25sqin but with 4,000w i would need 47.25sqin, 1,000w is 23.75sqin. You see how power is very relevant in these calculations for designs that need as much space in small spaces as possible. So... In this design i am doing, i need 41.25sqin of port area for this box. If flared ports decrease the required port area required,(meaning i can make a flared port that takes up less space in the box and still get the same results as a slotted port) how much do they decrease this requirement? Complicated question? I am very curious to know how small can the diameter of a flared port can be made to keep your DIY applications to fall within your personal limits of port velocity to retain as much NET volume as possible. I am also curious to know how I go about calculating the volume a flared port takes up? And no i do not have any measuring device methods such as filling box with water.