China.
What THEY say, take if for what it's worth: Their prices are low compared to the Jap brands because labor is cheaper and the entire machine is built in-house. They have no supply chain expenses like other manufacturers. Their initial business was making engines for others. Then they started building the rest of the machine to go with their own engine.
Note that during this thread and in other discussions, I've heard no one knocking their quality. Everyone who has one said it's a good machine.
