Hey check out this link Welcome to Atrend Usa at the bottom of the page they have boxes specifically made for the solo x subs and it lists some of the specs too. You might find the info to be useful. Hope this helps.
Start off somewhere around 1.5ft^3 tuned to 48-50hz. With that much power on tap you might have to go smaller to put that power to use without ripping the sub apart.