Congrats to Jim on another article in print! This Months AudioXpress magazine (link to AudioXpress website) contains another article by Jim. Titled ""A Flared Port Study", Jim does a direct comparison of a straight vs. flared port tuned to the same frequency. Impedance curves were checked to confirm the correct tuning and then impedance and SPL measurements were taken at different power levels. The article is a good read and I learned that a flared port must be longer to tune the same as a straight port (I thought it was the other way around :b, but I have never used a flared port). Jim, if you still read this group, I have some questions to ask. Since large flared ports (4" and larger required for big powerful subs) are difficult if not impossible to find, maybe a study on how much flare is required would be helpful. If I used a straight port with a 1/2, 3/4 or even 1 inch radius routed flare, would that work? Or is an elliptical/parabolic/aerodynamic shape required? Also, what diameter of straight port (if any) would produce the same results as the 3" flared port tested? Just some thoughts that come to mind. Good article and I recommend it's reading by the DIY community.