I have two Dayton HO 12" subs, each in a 2.0ft^3 box. They sound good, but lately I have really been missing the lower octave. I modeled these in winisd pro and found an F3 of 60hz, which is completely unacceptable for a HT setup. After some quick modeling, I found I can add a 4" port that is 23" long and get basically a flat response (-1dB) to 30hz, which is fine for me. My question is, how long is too long? Has anybody run a port of this length? at 30hz my port velocity is 28m/s, which is a touch high but not offensive--plus the ports I purchased are flared to over 5", so that should help. Is 23" ridiculous? Will it affect sound?