[Cloudsurfer]

You are correct, to a point. The cats in the headers are "pre cats" and are there for quick warm to curb emissions after a cold start. The main cats are the set in the mid pipes. However, as to causing problems with passing emissions, removal of the main cats will throw no codes, as the cat efficiency monitoring uses the oxygen sensors before and after the pre cats, so removing the secondary cats has no effect on this process. Now, if the smog tech knows enough, he will notice that you do not have secondary cats and could fail the visual. Removing the pre cats in the headers is a lot more work when trying to keep the DME happy.