You will *not* achieve an f3 of 20 or 25 Hz like you can with a woofer like I mentioned with 99% of all home drivers, including lines offered by Eminence or JBL. I speak from personal experience. Maybe if you can afford absolutely giant enclosures they might work fine.

Most pro woofers run lower Q values and higher fs values to make them effecient. These are not exactly golden parameters for super deep bass response.

Kilomax 18's even in largish ported enclosures won't go flat to 30 Hz. You can get a tempest flat to 20 Hz and it has the excursion to handle it.

Adam