'06-lx470. When the truck is warmed up, you can hear the cat(s) making a light popping sound. It sounds like someone hitting a metal pan with a screw driver. Once you turn the truck off, the sound is more prominent since the engine noise is gone. Does anyone ever hear this noise? How would I know if the cat(s) is going bad? I think their is a 80k mile warranty on all cats per the emissions guidlines. Thanks for the help.