Excellent marketing of an exhaust system! For the little money involved in tweaking an exhaust for the performance crowd, the payoff had to be there, but so few OEMs took advantage. Lost opportunity.
The issue with "The Humbler" was the fact that you have to take into consideration the time period. Sure, they could've built it out of stainless steel, but nobody would've paid $895 for what amounted to "a toy". Price was a big consideration, so they made it out of regular steel - I don't even think mufflers were aluminized back then, either! Secondly: Warranty. The reason the option was recalled and then deleted was that most of them rusted up and stopped working costing GM a lot of headaches and money. Internally, it was a controversial option among management, so add in warranty issues and Uncle Sam sticking his nose in the automotive business, you can start to see why it never caught on. I'm pretty certain that by 1970 even California had noise laws. Lots of the Hi-Perf cars destined for CA had mandatory turn-downs.
