I would strongly recommend the IRS ( Individual Review System ) to anyone with a desire to speak Japanese like a native in a short amount of time.
In my two years with JACS, I was able to pick up the accent and pronunciation quickly. As their class put a lot of emphasis on speaking not just one speed, but more important, talking as if a native was speaking Japanese. In a short period of two years, I was commented by my Japanese friend that my Japanese is as good as any native speaker.
I have returned to the States for more than 2 years and people were still surprise I was not Japanese when I was in the Sushi restaurant !!