Hello, I am trying to design an enclosure for my tempest but I need some help concerning the design and construction of the port. My enclosure plan is very unique (IMO), it consists of 1 Adire Tempest 15" Driver and 4.75 cubic foot 3/4" MDF enclosure. I plan to have the enclosure Sealed 99% of the time for sound quality purposes, but I would also like to include a 4" wide 1.44" long "pluggable port" tuned to 40hz for SPL burps. I was wondering if anyone has experience working with PVC and could give me advice on this project. First, I need to know how I should "flush mount" the end of the PVC tubing to the surface of the MDF. Is there some sort of Flange I need to purchase? If so, what is it called? Does anyone know if having threads inside the PVC pipe will significantly affect the acoustics of the subwoofer? Also, Are there any adverse mechanical affects of having such a short port? As long as it is safe for the driver I am OK, since I will only "unplug" the port for SPL burps where maxium peak SPL below 80hz is desired. PS: This enclosure is going in a car but that shouldn't really matter.