Robbo, you can make your own piano sound by modifying one of the onboard sounds to fit your requirements. It's very easy to do.

Attached is one I created several years ago and it has been downloaded thousands of time. Just unzip the files, copy them to your use drive, then press any instrument category, tab to the USB, then select the piano voices I created. It works fine on all Yamaha arranger keyboards.

All the best,

Gary