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What's the purpose of this metal on the exhaust, it has a rubber cushion but it never touches the fender, there is space between them.

It's there to offset the aluminium exhaust shield. The air gap between the shield ensures that the shield does not get too hot. Especially if a passenger or a load touches the exhaust.

The aluminum shield is not related to this part. this part is under the right fender. See here:

well, I belieeve the reason is the same as mentioned above, just regarding the plastic paneling instead of aluminum heat shield:
To ensure this part does not directly touch the exhaust, even if loaded.

Yep, 110515 is right, that's a bumper to make sure the fairing won't touch the exhaust, especially when there's a bit of pressure on it, like from saddlebags or a passenger.

The space between the fender and the bumper is very large. It will only touch it if you bend it hard or if the motorcycle falls. Why didn't they make it farther away so it touches the fender?