I am trying to find out what will be the best sealed box for these woofers. I mean like cubic feet. Like how much space do they need to hit the hardest. They are going to be powered by a Orion 600D mono amp. I have 2 kicker comp cvr's right now and I dont like how they sound.
How many subs, you didn't say?
If you're talking about two subs, a box of a total 3 cu ft net will "hit the hardest". A box of 4 cu ft net will be best for SQ. With 3 cu ft, SPL will hit 118 db at 80 Hz with 600 watts input power. Low end response is not unreasonable. Neither one of the sealed boxes (which is what this sub should have) will peak outrageously for added decibels. The SPL for the 4 cu ft box is maybe 1 or 2 db down from 118 at 80Hz.
I would build for 4 cu ft for the two subs, if it were me. And I would also buy a more powerful amplifier and run the set of subs at 4 ohms onto the mono amp. For real SQ.
-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.