yeah getting ready to order box says 33hz math comes out to 35 (after sub) so they pretty accurate., thing is I thought my hp recommended 1.75-2 cf box (1.81cf ad) which I had left from my pioneer (perfect for it) can't find my orion manual, saw on post somewhere it takes 2cf but online manual says 1.45 cf so my box is to big for power I have now I think (like I said boomy) so for my sub I'm getting box that works out to 1.56cf ad (it says 1.75 but I have a calculator) should be good but if I change to any of these other subs they will want more air so kinda screwed if I get smaller box and aint happy, well I'd still have other box but it's tuned to high since I cut port probably 40hz now (loud though).. I could screw plywood into slot port (against box wall) make port smaller tune lower is another thing to try, port calc says it works..