I heard an unsettling noise when I engaged SPORT mode turning on the ICE last week. It was the unmistakable rattle of exhaust vibration. I was able to put the Karma on a couple of ramps and crawled under to discover one of the pipes from the Center Pizza Box muffler was completely cracked all the way around just beyond the re-enforcing strap that was placed on the new level triangle muffler. It seems the design may have only moved the stress point to the point where the welded strap is located. Sorry, I didn't take a picture.
The good news after realizing I couldn't fix it myself, I took to a local muffler shop. They welded the pipe in 2 minutes and was good as new. Rattle is gone, muffler is working again. No charge! Beats paying $1200 for a new muffler.
The muffler was replaced under the Customer Appreciation Program a few years ago. It probably had less than 10K miles of ICE driving. Wonder if this is common to the new design.