with only 1 or 2 exeptions Hi-flow cat = No Cat. Without any type of catalyst the CEL will be tripped after a very short distance, and you will not be able to pass any type of emissons. Honda cats are very free flowing and getting a high flow cat doesn't really anyhting. (don't take my word for it, see if you can find one dyno graph to show a gain from the cat alone.) I would just chalk it up to a lesson many of us here have learned and throw the stock cat back on.