Bo,

you can surely not upgrade your PSR8000 with PSR9000 or Tyros sounds, but you can get sampled voices, which are from the quality point of view compareble with at least voices from the PSR9000 or the PRO.

Check http://www.cd-soft.de/PSR_9000_News/PSR_8000_News/psr_8000_news.html

for details.

Ulrich