At 12-1500 rpm other then when in forst taking off from a stop light you are probably loading up the motor. Even woth a lt4 cam that low of rpm is bad for it unless on highway or just starting off in 1st and even then should be minimul throtle. The converter may or may not be bad. May be whatever the tune is set to is making the cat smell. Or it could have made it go bad no way of knowing wothout knowing whatthe car is doing.
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2000 SS Procharger
98 Z vert turbo
07 TB SS cai catback and tune
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