bc13brad

Thinking of removing my cat to premix but if its going to cause it to run lean that would be worse. Does anyone know if it goes rich or lean?

Loki

iTrader: (1)

It won't affect the mixture, the post-cat O2 sensor is not used in mixture calculation.

Also you can premix with a cat, just don't go crazy with the premix amount.
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CaymanRotary

I run decatted with both O2 sensors. Judging from my plugs it runs slightly rich if anything.

dannobre

iTrader: (3)

It will still run super rich at WOT. The only way you can fix that a bit is with a flash tune

It won't really give you much performance wise though. The AFR doesn't make as much of a difference to the power output as you would think.