Years ago a rugby colleague rebuilt the exhaust on his car. Basically replacing rusted pipes with copper pipes. It certainly changed the note of it! They didn’t last that long though. I think Pagani used titanium in one of their cars and included a resonator to tune the note. It was also heat treated to give a purple colour.
Pops and bangs are no substitute for a nice note. Another thing that makes me laugh are the dump valve whooshes that people create. OK for racing to help turbo effectiveness but on a road car? They make me think the car has asthma.
Or Inconel perhaps ?