I guess the back wave from the subs would carry through the attic but don't know what it would sound like in the house. With all the insulation in most attics I wonder if it would be even a problem. Though a 100db-120db at 20hz is bound to shake the whole house anyway
My subwoofers are in dual 3.4ft^3 sealed enclosures and I definitely have sound transmission to the outside world! You get this with any type of subwoofer in a listening room unless it's very well isolated from the rest of the world!