Thanks, I've been all over those sites.
I recently knocked up a pair of enclosures with a little software help and reference to other DIY designs. It was about 90 litres and tunes to 35hz (give or take).
The results were mixed. The mids and highs were perfect of course but the extended low end had issues. Depending on the music the bass could be tight or reeeealllly bad. Seems like trying to get more than they were designed for has it's limitations...
Next up is going to be a smaller box, based on factory specs. I will be updating the XO with modern spec components.
If anyone gets a chance to pick up a pair -- HIGHLY RECOMMENDED. They are not for every type of music, but they do sign beautifully with the right material.