The Yasuni Z" is a surprisingly powerful exhaust system that needs no other type of customization. It also works with a 70cc cylinder. Yasuni Scooter Z is Yasuni sports-street exhaust with weld-in restrictor plates. Yasuni Scooter Z has e-pass / noise restrictor plates welded in the muffler and header inlet. The piping is also built around the stock center stand unlike the Carrera Racing 16 and 21.