Start taking some of the advice people are giving you. So far your product choices and decisions on items is poorly lacking. While those pioneers may be better than the sony's.. there are FAR better subs for the money. And the fact that your even still thinking about that prefab box appalls me. People sell box plans on here for $10
And thats to put it in good words.... some one can something like "Listen *****, if your asking for advice take it and not just act like a wise *** and make your own decisions, that box blows my dog Terry's ***, and shes a beagle. And those Sony's is what i use to clean my backyard with."
Like stated above, dont replace crap with crap, with $200 you can get yourself a good sub that will pound 4 of those sony's away. And making your own box for around $35-$50, and this being your 1st system it will be awsome.