It's well documented that mini cats/o2 extenders do not work in our M3 but what about pairing them with HFC?
I have Akra full exhaust with HFC and have been thinking about adding mini cats like these.
https://www.fabspeed.com/universal-9...nverters-pair/
I understand these will not pass visual but will the combo setup allow O2 readiness and prevent CEL?