Break-in oil and the ZDDP content would kill a catalytic converter relatively quickly. Part of why ZDDP content has gone down so much over the past 20 years is the EPA mandate to have emission systems warrantied 100K miles while having total overall emissions low as well.
Now the necessity for break-in oil for a hydraulic roller cam engine and modern machining tolerances? Not that much. Personally I still do the 600-1k mile oil and filter change though. But if you're doing a dyno tune/break-in then swap the oil right after that and run it through a screen.
Now the necessity for break-in oil for a hydraulic roller cam engine and modern machining tolerances? Not that much. Personally I still do the 600-1k mile oil and filter change though. But if you're doing a dyno tune/break-in then swap the oil right after that and run it through a screen.