I have a 2006 HHR 2.4, I'm replacing the cat and both o2 sensors. The 06 has the upstream sensor in the manifold and as I understand many of the later years have it in the downpipe just after the flex pipe. New cat has 2 holes for the sensors. Can I move the upstream sensor down to the pipe (still ahead of the cat) and cap off the hole in the manifold or is the location need to stay in the manifold?
The manifold is already small enough, seems like there is more room in the pipe and it would be less restrictive.