Been around for several years and I was not aware of it until I saw a post on Reddit's "JustRolledIntoTheShop". Ingenious how a metal patch with holes in it can replace a large, heavy resonator. The article is from 2019 and the tech is making it out into the world.
https://www.asme.org/topics-resource...omotive-design

 

Fancy. I wonder if there's a way to purchase these for the aftermarket crowd.