Ok, I've learned alot from my first DIY Tempest I built 2 weeks ago. I guess you can say I am now addicted to low bass and want something even better than the SBB4. I've decide to do 100% of the project myself. This means I'm gonna actually create my own enclosure based on my own calculations instead of copying Adire's reference designs. I basically want something along the lines of the Adire Alignment, but in a 18" x 55" Sonotube enclosure. Here is the specs on the enclosure: - 18" Sonotube, 55" tall - 219 Litre enclosure - 64 Ounces of Polyfil - 6" x 32" PVC Port Tube tuned to 16hz - Air speed of port is 9.47 m/s @ 16hz - Group delay is 16 ms @ 20hz - Passive sub with bi-wireable binding posts (to take advantage of the DVC) Anyways, any thoughts on the sub plans ? Is there anything I should change or does it look fairly good ?