Hi Jingleman
Very few keyboards use GM Drum kits except on Midi files, also Yamaha had their own format mapping (XG) which was slightly different to GM.
You will need to change the notes played on the PSR or alter the drum mapping in Cubase to get them to match.
Cubase first came out in the Mid 80s, when it became pretty much an industry standard. A few years ago Yamaha bought Steinberg to add to their portfolio, but they still develop products independently of Yamaha, (This is why you have a separate Yamaha section) so as to continue to support the Pro market.
Hope this helps
Bill
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