High Flow Cat for 95 GSR

Hey I just got a new catback exhaust system for my 95 GSR and I was thinking of getting a new catalytic converter soon. I know getting a high flow cat will increase the horsepower and whatnot, but which ones can you get and still pass emissions tests? Someone told me that "high-flow" means that it doesn't clean the exhaust, so I don't want to get one if its gonna mess up the air and not allow me to pass emissions. I was gonna get one off ebaymotors too, if anyone has experience with them, let me know how it went for you. Thanks.