I know I am new here but I think 2.2CF before displacement would be fine for 2 10" p5's. After displacement you should have 1.9-2.0 CF. I build a ported box for 2 12's (3.0CF@30hz). I used (2) 3 inch pvc pipes that were 9.75". Sounded way better than they did sealed.
So my suggestion: Use the...