better put how do you know what port to use my other boxes are based on cone area, EBP, and Xmax. Also is it possible to change the box volume for the motor cabinet. with the RF2210 i want to use 1 cu ft. also does the box volume include port and speaker. with a 9512 the sub is twice the box volume.

Sometimes PiAlign "thinks" a smaller port is acceptable, sometimes it chooses a larger port. But, except in rare cases, I usually find its port suggestions are reasonable for the cabinet size suggested. The times you might choose a different port are times when port installation is difficult or sometimes when a high-excursion driver would make port turbuulence a problem at high power levels. These situations sometimes require special port placement or size considerations. It often depends on your cabinet layout and intended use. PiAlign is a software tool that I've found extremely useful, but ultimately, the design choices are still yours to make.

How can you personally interpret that.

So then using a larger port I need to match the frequency and not the Q for it. Just about any sub a will be using will a al least 12" of Xmax.

also is there anyway to model a larger box with the program.

PiAlign was designed to iterate and find solutions to the forumulas that express Pi Alignment for a loudspeaker cabinet. To perform T/S analysis of a Pi aligned cabinet or others, I suggest using something like Carlson's BoxPlot. That will show you the response curve of a speaker using whatever alignment parameters you enter into the program.

If the horn cutt off is lower or the vented box is tuned higher than peak in the responce is created.

my next question if this is right how can you predict a peak in the box. say if the box is only going to be use for below fifty hzs. and you want more of peak below that use a larger horn bigger box ?

I know both programs and have been using Boxplot for awhile but horn responce is still new to me. But i still believe in trial and error for a box design but it helps to have a theory of how it will change then have a theory on why you got the change you did. for instance I built a fourth order bandpass that modeled good the the port was to small.