I've had both cats replaced. One at 30,000, the other at 34,000. The car now has 39,000. Since then, there is a rapid ticking sound when I accelerate. It gets faster with rpm rise. I know there was a bad batch of stock cats a lot of them failed. I also know new cats sound different. The car has no performance problems as of yet. It even runs better after the swap. Has anyone else noticed this? The car is stock aside from a K&N.

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2000 Camaro Z28 Monterey Maroon Metallic, A4 ,leather, 323 posi, Monsoon w/CD, T-tops, K&N

 

kind of sounds like you may have a slight exhaust leak. sometimes that can sound like a lifter tick. my .02 maybe the mechanic that put on the new cats left a slight gap or hole when they installed them.