I’m looking to build a ported enclosure for (6) Ampere Audio AA-2.5 6.5” D2 subs. They will be run on a 5k/1 ohm stable amp wired at a 1.33 ohm load. There will be plenty of power as they are 500 rms and 800 max. I can’t seem to get anything from Ampere Audio on the port size I need. With sub displacement my box needs to be 2.48 CF (+) port displacement. Does anyone have suggestions or know how to calculate the port size? Square inch and length is what’s needed. Hopefully someone can help on this