I have Japanese wii and I change region from ntsc-j to ntsc-u just by folowing this tutorial:
http://wiinewz.com/forums/faqs-guides-tuto...ystem-menu.html
My wii was 3.1j now it is 3.1u my modchip is wiinja deluxe and work just fine, just one thing bothering me is double weather and news chanel...