Why did no one tell me about these??

It looked like your typical beater UJM/café mashup (at least from a side profile) but THAT SOUND. How..? The owner did a few runs to redline and by the end I was laughing like a madman. I don’t think I’ve felt a reaction of this strength since the first test drive in my Miata.

Here’s a few videos of said bike. I still can’t wrap my head around the fact that the above bike and that sound go together