I've noticed a weird metallic rattle at idle. I thought it was just the exhaust or a heat shield. It got noticeably louder and I stuck my head under the car to see where it was coming from. It was coming from the catalytic converter area, but when I put my foot on the cat to stabilize it the sound continued. I also found tiny white flecks coming out of the exhaust. Removing the cat today, I see that my 3" hi-flow cat is not living up to its name:
The rear section of the honeycomb broke free and turned sideways. It almost completely blocks the outlet. I bet the car is going to run a lot better with a new cat.
