Is there anything I can do

Systems

In the little book that comes with each subwoofer, talking about building a box, there were plans on building a box enclosure. I built the box exactly as is says. Now after the 2nd time my subwoofers broken, I reexamined the box i built and the book, I read in the book that it would be great for 2 10" woofers. I have 2 12". Can anyone make sure that im correct, that the specification are for 2 10s. And if they are what can I do? How much space does it need to be increased by? or decreased?

Systems

Well i have had the problem of the lead wires ripping off the cone and the terminal, and the only thing I could think of, of why its doing this is the box is to big, like the subwoofers excusion is pulling them off. If I make an object 3.5*2*1.5 that gives me 10.5 space, if I place a peice like this in the box is should come close to the .88 right? And then it wont do this will it? And someone told me that it might be air leaks, well if u make it a bandpass box, would it be like the same thing, the wire should rip off.