I read on another site that if you replace your 4 factory cats with 2 high-flow cats that it will cause your air/fuel ratio to become richer. Does anyone know if this is true or not? I know that I lost 1 pound of boost by replacing the factory cats with the high-flow cats but my truck still feels quicker with the new cats. Maybe it just allows the motor to work more efficently??

 

It shouldn't be affected by the high flow cats. And if it IS, then it's a false drop being read after the cats anyway. If you checked A/F before the cats, you'd likely not see any change.

 

Thanks Sal!