Here is the prove for Mario Kart Wii - JPN retail version working at a US Wii which is Ver3.2U+Wiiware update without any modchip.
http://www.youtube.com/watch?v=_hBt-pRulao
P.S.: Play-Aisa and some user said its not working, but I can play it normally.
http://www.youtube.com/watch?v=_hBt-pRulao
P.S.: Play-Aisa and some user said its not working, but I can play it normally.