Hello,
I hope this is not considered advertising, but anyway...
I designed a horn around a pair of very cheap MCM woofers about two years ago. MCM discontinued the woofer right after a buddy finished building the horn, and Jerry McNutt offered to take a look at issuing something similar, sort of as a Lab10, but obviously it can't be called a Lab10 because the LAB was not involved. I redid my original horn for a slightly different (better) set of woofer specs, and that's where the HL10 came from. I finally got the horn built a few months ago and am about done testing it. We're (Eminence) planning on putting the plans on our website. This horn is fairly big (4'x4'x18.5") and is designed to go in large home theaters. I also came up with a smaller design (30"x30"x13.5") that uses one HL10 and can be used ala the LAB sub. A stack of 4 outside looks good, while a stack of 16 would be smokin'. I am working on getting this one built and tested.
As far as modeling up horns for it on your own, I would look at very small rear chambers, not large ones, and medium to small throats / front chambers. I have also used 4 of them in a vented box for bass guitar. It's 24"x24"x15" and uses two square ports 4" on a side and 28" long that run along the top and bottom back corners of box, venting out the sides. This gives it an EBS style tuning at 30hz.
John