IDMAX Ported Enclosure

Good luck building a p/r box, I hear it is a very precise and exact science.

A specific SPL box for that sub is a ported box. An there are variations on the size of the ported box as well they (ID) give you some samples for sq/spl vented enclosures, in other words they sound good and get loud (tuning freq.) However that sub is more or less a loud sq sub, but don't get me wrong that sub will get plenty loud.

If you are looking to just have some mind numbing bass, find something cheaper and more geared towards that. 

I recently spent some time on the phone wih one of their techs, discussing similar questions. I suggest you do the same, they are very helpful and REALLY like to talk.  

Go to the PDF spec sheet for your sub http://www.imagedynamicsusa.com/pdf/IDMAX12-V3-D2-spec.pdf

Large is an I.B. install, medium shows a box size.  Both show port sizing, parameters, etc.  Note the frequent advice that you should call for technical assistance with this sub if you are setting up a comp vehicle.

should i listen to Image Dynamics reccomended size or should i look elsewhere -- i've heard they're not always the best sizes for maximum performance. I've decided just to make a sealed with this subwoofer and they reccomend 1.3 cu ft for the "medium" sized enclsoure -- im willing to go to 4-5 cu ft if needed