Ah, I see you are getting ready to build some horn bass units, made of poured concrete extending back into the yard as far as necessary, as some of my Barbados clients have done. Screw folded horns when you have all that yard for 50 feet or so of straight ones.
One client there also copied the cabinets of B&W DM6 speakers out of concrete too, built into his listening room walls. Actually VERY good sound!
Frank