Does the cat alter lambda readings?
 

I am thinking of removing the downpipe cat on my MY03 STi.

Will this cause a CEL error??

Does the cat alter the levels of oxygen in the exhaust??

It'll cause overboost as well, dont do it unless you have a remap sitting waiting !

I am desperate to give mines a full decat, but dont want to risk blowing it for something so simple IMO

Stephen

PS it will bring on the CEL as well;) & you dont want to do that !!