You're probably not giving the Kicker enough room. Unless it's a Solo Classic Kickers like big ported boxes. The AB is also going to like a big ported box. How much are you looking to spend? Polk's MM's are great and like a small box. They're also Marine Certified. Here's a link:american bass,good or not for my application?? tank's
Because they want you to buy more subs to fit in your space available (more sales), as oppose to fewer subs operating efficently.last question,why kicker recommend 0.6 to 1 feet cube box for sub and the reality is more than the double!!