Just from my experience as a tech, becareful with some aftermarket cats, after a short while some people will experience check engine lights due to poor catalyst efficiency, basically they dont clean the air properly, big cluster f*ck! Cant say I have experience with Evo's cats though...By the way , howcome you think you need to replace them?
Yeah, but that rattle could just be the heat shield that needs to be tack welded back on. Nothing more, nothing less. Just offering up an alternative suggestion.
I had mine welded back on when I bought the car, and after about a year or two it's back. I'm guessing I'm just going to bring it in again to get the shield welded back.
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