clattering

Hi Guys, My factory has started making an awful clacking/clattering sound from around the top end under load from cold. Once up to temp, the noise largely disappears. Also using anything other than 98 octane fuel is causing huge amounts of engine vibration. Not sure if these issues are related...

So I've had my bike for a few months now. It's an 01 Mille with just over 31k miles. It all runs as it should with no issues since I've had it. I changed the standard exhaust for a fuel F1r carbon exhaust about a fortnight ago. It's had no issues with the baffle in or out except on Thursday...