I have an 18'' Q and I saw that you recomend 6 to 10 cubic feet. What would be the difference in having a box that was 6 cubic feet rather than 10 cubic feet. I was going to tune to 28hz and I listen to country, rock, and rap about all equally. Will the smaller box change on how the sub performs and sounds? Also what's a good idea on how much port area to have. I always get told different answers. Some say 10 inches per cubic foot than some say 12, 15, 16, etc. Thanks