im finding a LOT of things interesting,
1)why would somebody recommend the BREAK in of sub in these situations? the people are saying it dosent sound loud, a broken in sub isnt gona give him an extra 12db were it will become loud. Subs will not gain 3db after being broken in.
2)Why the hell are you giving a sub 1200 rms if its rated 600, i dont care who says what , you really got to stop listening to people and look at the drivers numbers obviusly engineers and designers arent going to lie to you and if you think people know more than them thats you.
3)I HIGHLY doubt that going adding .35 cubes is going to fix this problem, go get some pollyfill and you will see. And you need to go to the god **** website and find out the information on the subwoofer, it dosent make sense to GUESS randon enclosure volumes, again to the website it will tell you what enclosures that sub will work in, again engieers and designers are not gona LIE to you .