I'm assuming it is specifically designed/sized for it.
I did a search and couldn't find any other mention of the new designation anywhere, so at the very least I believe it to be a new IHI configuration. I've been trying to get CFM numbers. If someone can refer me to a page that can calc it from impeller size, A/R, port diameters etc that would be helpful.
Subaru have been very careful with the selection of components for this car, especially with the engine and driveline. Everything is "just right".