wood thickness

https://www.the12volt.com/installbay/forum_posts.asp~TID~74592~PN~1

Looking at the size of the enclosure which at 4 cu ft is pretty large, I tend more toward supersizing the wall thickness.  Things you should look at are the stress point areas of large baffle expanses.

The spots marked in yellow are the weakest points on those baffles.  The face baffle is the critical component because it has to provide the footing for the woofer beast while at the same time have a large hole cut out of it.  Saying, there is less of this baffle due to the cutout, and more stress applied because the woofer is attached to it.

Depending upon what materials I have on hand, I would tend to go double thickness on the face baffle for this build.  Double 3/4 or double 1", whatever you have.  With adequate bracing at the stress areas, single ply 1" for the rest of the box.  If you have 3/4", look into shortening the expanse areas between braces.  Thicker is always better in the large subwoofer enclosure build.

And note:  there isn't a difference  because it's a ported box rather than a sealed.  The function remains the same, and loss of dynamic sound due to wall undulation (stress) applies with a ported box just as much as with a sealed.

well..just to keep the threads low...thought i'd upload a pic of the install.

sorry for the fuzzy pic...but it's a 1500 watt MTX amp, power acoustik 10 farad cap and a 15" RE XXX sub sitting in the back of an olds alero.  the center peice where the cap is sitting will be covered with a tan vynal to match the interior of the car.