I had in mind to build a 'Joe Blogs Briefcase' using FaitalPro 5 inch drivers, but when I feed their parameters into WinISD I'm getting port lengths of over 300mm which does not look right. Can anyone be bothered to input the TS parameters for the FaitalPro 5FE120, for a cab with two 4 ohm drivers and a volume of 9900cc tuned to 70Hz with a 12dB/octave HPF with a 30Hz turnover.  My clculations give -          For 30 watts I need a slot port 150 mm*20 mm by 132 mm long giving me 17 m/s