I see the recommending tuning is from 27-33hz. How do those number compare? Is 27hz going to loose a lot of top end compared to 33hz? Does tuning on the lower end of the range actually gain a noticeable amount of deep bass production>

I actually prefer them sealed, IMO...

I gave a range, because my ears may prefer one tuning, where as someone else might prefer another. We did not want to tell people this is exactly how to build for it because everyone is going to have a different preference, so we gave suggested range to start with.

Why not describe what you want and ask what we'd recommend?

Alright, I've been doing measurements and hand drawings feverishly all yesterday.

Some measurements are set and some can be modified.

The box can be 40" wide and 15" tall. Those are the maxes. Depth is changeable, but I've been thinking of doing around 12".

I am planning to do a square port, 5.5" x 5.5" pointing up out the top of the box through my open 6x8 rear deck hole. The sub will face the rear of the car.

Here is a nice picture showing something similar to my idea for the square port.

Why not describe what you want and ask what we'd recommend?

I meant acoustically

Interesting port design.