DATS is really great I'd highly recommend it. One click of a button and you get most T/S parameters for free. No messing around with building a jig and hooking it up to your sound card. It doesn't get easier than DATS. The only tricky thing is getting Vas and Mms. You either need to attach a precise mass to the woofer, or use a test box with known Vb. But well worth it for the predictable results.
Will post more - I bought two walmart subs, just built a ported sub using the other one. It's hilarious. Has two port tubes and they stick out the top of the sub. Will test it, write a post. Although it'll be much smaller since fewer mistakes were made :D
I'll definitely check out your posts! Always been curious about horns.
The ported subwoofer box should be quite interesting!
I don't think it matters if the port length is in the box or outside the box, as long as it's the right length.