Disappointing dyno results 370z 7at

synolimit

When testing a car with my ported parts the customer had cats too. Just an example of what can happen he was 4-5 degrees less timing then mine, and 2 other friends who are catless. and he even had berk HFCs. Conclusion was the cats heat up and hold a ton of heat. That heat creeps back to the motor starting knock which is why we pull so much timing.

I never researched it but I'd be curious if it's the heat more or the flow restriction that kills HP with cats. If it's heat I wonder what a cat does back further like in a mid pipe or muffler. Is it even an effective cat back so far with less temps?

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13 370z-