Ok, they've probably patented it but has anyone noticed the new Klipsch sub with the port diagonally in the box? It's the most obvious cheat to get lots of length without bending the port, can't believe I never thought of it. They run the port from one corner (more or less) to the other corner. It's amazing how much length you can get that way, for example a one cube box has a maximum diagonal of 2 feet, and in general for a cube the maximum diagonal is two times the side. A 'rectangular' box wouldn't yield quite as much benefit, but still some, and sometimes a modeled design comes up just 6" short of where you want to be... This would probably work best for large(ish) cabinets where the driver motor didn't interfere with the port location. It would require some creative cabinet work at the exit, but might be worth it in terms of not having the cost of PRs. Interesting, anyway.