I just purchased a 2013 Ford Fusion (daily driver w/better gas mileage than my F150) and wanted to build a dual ported enclosure for my Sundown Audio SD-2 10D4s since I now have the room. I designed a ported net 1cuft per sub enclosure. Using a 33Htz tuning frequency with a 2.5″ diameter port, I’ve calculated the port length to be ~10.32″. A slotted port for the same tuning at 1″ wide 11″ high, I calculated a length of ~23.98″.
In my research for my new enclosure design, I found an Atrend enclosure on Amazon for $69, and with my Prime membership it’s free shipping! Materials for the box I would build are nearly this price. The Atrend enclosure is an ideal volume, net 1.0cuft per sub, the Sundowns displace 0.08cuft for a 0.92cuft net (SA recommends 1.0cuft for ported so it’s darn close). The box is made from 3/4″ mdf, however the front baffle is 1″ thick mdf. The enclosure is tuned to 41Htz. with a slotted port measuring 1.25″ Wide x 11.5″ High x 22″ Long.