I know that there are some 3rd parties in Vietnam who did the expansion memory upgrades on older Yamaha PSR-S series arrangers, but I do not know if there are such companies in the U.S.

Every time when you install an expansion pack, or a combination of several expansion packs that fits in the allowed expansion limits through using Yamaha Expansion Manager (YEM), the expansion flash is reformatted to prevent fragmentation.

The expansion flash storage is read-only after pack installation. However, through WiFi, YEM can perform minor expansion pack updates on Genos without reformatting the expansion flash. I never tried this on PSR-S970 though since it does not have built-in WiFi.

PSR-S975 has 768MB of expansion flash compared to 512MB of PSR-S970. So it helps just a little but not much. I have to be selective to choose expansion packs for even the 1.8GB expansion of Genos.

We can pick and choose expansion packs or contents of expansion packs through using YEM, which slowly calculates / indicates whether limits of expansion installation pack are exceeded or not.

If you have many expansion packs for PSR-S970, the best strategy is to select different expansion packs based on performance themes / usage, and produce different PSR-S970_PackInstallData.cpi files accordingly, and rename these files according to the themes / usage, and store them at the root directory of the USB drive. In this way, you can install / load the ones that you need any time.

Thanks,
Paul