subwoofer design and porting

[rodney11]

this is what I have a cerwin vega 150 wat plate amp and 2 apex jr 8 inch subwoofers specs are fs=47.74, qms=.334, vas= .376 cu ft, qes= .552, re=2.653,le=.157mh,z=3ohms, bl= 2.287, pe=250 watts,ots=.514,and spl=85.22. the manufacturer recomends a vented box. I went to linearteam web site and installed WinISD beta in order to get the box volume that I needed which is 1.674 cubic feet with a 4 inch port in which this should give me a tuned frequency of 37.26 hertz. My box of choice is a cube with the measurements of h=24inches, w=12 inches, d= 13.5 and I would like to put the port in the middle between the 2 drivers my question is will this work and on how to figure out how much volume needs to be added in place of the amp the speakers and the port.