I don't remember off hand how much port area I have, but my 2 x18s on a saz3500, I play that version of sail that hits 10, 11, and 19 something like that. Tuned at 29hz, 14 ish cubes net. Once with one x18 listening to "bass I love you" I think I heard it bottom, but not sure, only heard it sound like it smacked once. Might have been something in the burban breaking, I dunno.
I love me them lows, tho.