I hate to break up the rainbow love-fest but.......
Asian women, specifically South Korean women, probably have smaller vaginas than African or European women or at least are culturally conditioned to expect less in the endowment area. However, a typical rule of thumb when it comes to penis is that bigger is usually better because vaginas can expand and accommodate babies. Furthermore, if you're not Asian yourself then packing something bigger is probably expected from Asian women (why would they alienate their culture without getting some upgrades in the process?).
For So. Ko., South Asian, and Chinese women I would say the 7 by 5.5 is a more ideal target than 8 by 6. Americanized Asians, Phillipinas, Japanese and certain Chinese women probably want closer to the typical American woman standard of 8 by 6. Body size, past partners, and cultural conditions also factor into the decision, but race is a pretty good barometer of what to expect.