got a box design for ya it will be 3.408 cubes tuned to 35.5 hz with 58 sq inches of port.
your port will be consisted of 2 pieces in a L shape.
your box will be
port will be 4" width for your opening
heres the cutsheet for your box:
top and bottom plate: 30 x 20
left plate: 19.25 x 14.5
right plate: 18.5 x 14.5
back plate: 30 x 14.5
front plate: 25.25 x 14.5
port 1: 14.5 x 14.5
port 2: 8 x 14.5
if you wanna see the actual 3d box design go here and type in the dimensions:
RE Enclosure Calculator