I agree with you that some "cats" marketed as "high flow" do not have the honey comb material inside. My point is that these are not cats but just tubes as you say. In order to pass emissions you need a cat in the true sense of the term, not in the 25 $ ebay high flow sense. Check to make sure it has the material, if not, it will not pass emissions. Ridiculous claims of 200% increased airflow usually signify that you are buying an expensive tube, not a cheap "high flow" cat. Sorry if I wasn't clear.