I've never heard of many people having much luck with changing to a high flow cat on an obd2 car. reason being it doesn't drop enough emissions through the cat to not set a code with the after cat o2 sensor. Personally I think it's a waste of money to waste time trying to gain horsepower from the cats, honda's cats are usually pretty free flowing as it is. I removed mine and put a straight pipe and if anything it just feels like it lost low end power.