Help with cleaning a used HKS exhaust

SouthArk370Z

1) I'd try a Scotchbrite (or similar) pad and some general-purpose metal polish. But that may not give you a mirror finish.
2) No idea.
3) Definitely replace. The corroded threads on the fasteners will chew on the tubing every time you turn them. Make sure you clean all rust/corrosion from the tubing where the fasteners are screwed in. I suggest using a small amount of anti-sieze compound on the threads to minimize future rust/corrosion (a little dab'll do ya).
4) My guess is that it would cost more to fix than it's worth. YMMV
5) If it's stainless steel, a light scrubbing with clean water should be enough to remove any corrosive road chemicals. You might want to blow some warm air through the tubing before storing to dry out the inside.

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