The soundfont of the Mario Kart DS Credits theme ripped from the game's files using VGMtrans. Also sorry for my lack of activity here recently. I was just extra busy. Really quickly, thank you to everyone who supports me! Enjoy!
I don't actually know where the samples come from. I know that it some of it might come from the MOTIF Rack ES according to the Newer VGM Sound Sources Sheet? But I know the whistle comes from the Sound Ideas Sampler Library.