I have always done slot ports in the past and have been very pleased with the outcome, but I am planning on doing a round port this time around. I have a 15" sub with an xmax of 24 mm and I'm looking to put it in a 4 cubed box tuned at 32 hz. I was wondering about the port size. I have always heard that a 6" port would be fine for 15, but after looking here http://www.carstereo.com/help/Articles.cfm?id=31
they recommend a 10" port diameter. Now I doubt i'll ever get the sub at full xmax, but I plan on getting enough air moving that I don't know if a 6" port is enough. I plan on making my own flared port. Do you guys think a 6" port is enough or should I look into an 8" port or a 10" port? The sub will be run on a kicker 2500.1 in a Mazda 3. The reason I want to do a round port is because of aesthetics and also the round tube doesn't displacement as much air as wood does so it will save me a about 2"s of very premium trunk space.