It's a fact that all exhaust pipes will eventually rot. It's a fact. And the more you use the vehicle, the less the muffler corrodes.
My brother's father in law has 3 taxis that are used in 24 hour shifts. After 4 years, the mufflers are intact.
Got you beat there Pat. I got my bike in 1987, it was fitted with an after market 2 into 1 pipe. almost 2014 & it's still on (& shiny!) We have to face facts that chrome just ain't what it used to be. I've seen plenty of newish Jap bikes with tarnished/rusting/bubbling chromework.
Just for information's sake the collector box on my the old Honda cb250/400n was a weak point. Never tried the following myself but it was said at the time that you could remove it & wrap it with cling film. replace & run the engine until hottish thus allowing the plastic to melt over the box, fuzing itself to the metal & thus forming a protective layer of plastic over the metal. Like I said I've never give it a go myself but from all accounts it was supposed to work.