As my quest comes almost to an end, I find out that all I'm missing now is the port material / configuration. I saw at PartsExpress that a flared port could give me 3dB extra output over an unflared one. OK, that sounds a bit over the top to me. I was thinking about using unflared (ie, PVC) tubing for my subwoofer, a 170 liter box tuned at 18 hz. I'm getting a 14.5" long, 4" diameter port in order to get a nice airflow. Will I *really* be losing those 3dB if I use PVC instead of a flared port? What exactly am I ganinig by spending the extra dollars in a premium port? I'm asking you because I can't find a flared port around here, and PE would charge me $75 to send a pair of 4" flared ports to México. Compare this to the... hmmm... $2 I paid for 1 meter of PVC piping, and you get the idea. Thanks!