If I run the kicker cvrs in 2 sealed enclosure of .6 cu. ft with polyfill in both and its says for .8 is it a big deal or does it make much of a difference?
It depends on what type of sound you're looking for. You could be way off or spot on. **** the manufacturer; they don't know what you want out of your system nor do they know what kind of power you're running.