Originally Posted by wstar

FWIW, I've had zero CELs on my Berk HFCs, and they've been on the car now for about 1,400 miles. Those miles include a wide variety of driving styles as well as several OBD-II driving cycles (my little OBD-II unit shows me driving cycle progress). Obviously in the pictures we have, the Stillen unit doesn't have an extended tube for the O2 like the Berk one does, but I don't know what that really means in terms of results until we get some people independently testing them.