I never got a CEL when I had the Berk HFC. I did switch to the CNT RTP before I went FI and I did get one even though those have the bung extenders. I just put some steel wool in the bung and didn't have a problem after that.
Now I have down pipes and FI and no CEL now either.
BTW: I loved the sound of the Berk combo. It gives the car a very exotic sound. While I love my TT Z, I do miss that sound sometimes. I think there will be a 3" exhaust in my future.
I wish Berk made one.