Question though I never modeled or folded with throat area/volume. Just wondering how to interpret those numbers?
Well tis the secret in the sauce my friend.
When you do midrange horns you have to get even more finely balanced.
OK how to interpret the results.
I did the same manifold on all the horns. A square area 13" x 13" x 1". Lets you set your driver in place and gives you enough room for X-Mechanical. Personally I make a throat mounting plate. That is the 13" square piece with a hole cut out of it to accept the driver from the rear side of the plate. You can use screws if you are looking to save money. Number ten or twelve with a pilot hole the size of the screww shaft less the threads will help you get a good tight fit.
Again if you are on a budget. I have built many boxes out of OSB makes for a very strong box if you use the speaker builders secret weapon.
So you are doing offset horns. I designed the midbass so that the mouth could be done in a 15 inch wide enclosure. So if you do it with 1/2" material you are laughing.
The compression chamber is a part of the horn. You make the 13" x 13" x 1" box and cut out a hole the size of the S1 on this, and from here you start your horn. the hole is roughly 4 5/8" square.
Hornresp will give you inches on any hi-lighted number if you press F-6.