Hello Mr Bear,
Pearl and tama used to make a lot of their kits in Taiwan and they are really good quality for the money. Recently Tama moved its manufacuring plant to China to build the Superstar kits, and the quality is amazing I have one and I can't fault it. I used to have a Pearl BLX which is equivalent to the Masters Studio today and it was a fantastic kit also, built in taiwan.
For pearl, yamaha and tama all of their top end kits are made in Japan. DW top end is made in USA.
Now days where drums are built doesn't really matter because the company employs strict quality control to monitor the maufacturing process, so don't worry about it too much, your drums are just fine.