Lets agree to disagree on that then 
Yeah I was pretty sure most factory exahausts were stainless. I know my Mustang in 1991 came factory with a stainless exhaust.
eh…stainless > aluminized > hts coating
fine 
we will discuss it more after a bottle of cabo wabo
tha aluminized exhaust on my tib lasted 4 years and i handed it off to another tib owner and it still did not have any surface rust on it
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it’s not aluminum
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there is no such thing a “stainless” in the oxidizing conditions you find in an exhaust.