Yes ive been seeing some jdm manifolds on nasioc or the market place but none for the 08+ sti. Interesting enough if you look on some japan parts sites, you might be able to find what you're looking for. You will probably pay a premium for new stuff like this.I still am pressing UPS to how the box was cut open the way it was, and why they said the turbo went missing for sometime.
I'm not sure if the inlet is any bigger than a vf48. I considered porting, however I may just leave it as is.
I do have a leak on a manifold and up pipe. Its from a GD chassi however as they seem to be alot more common. There is a few sight differences between the GD style and the 08+ versions, but info is scare on that.
subaru・IMPREZA 4D SEDAN・EXHAUST detail of the parts catalogs with pictures.You can find the parts you want.