I've gotten my car to pass every year (3 years now) LEGALLY. When I had the B16 in the CRX I had a stock cat & it'd pass, but then when it didn't I used the "Guaranteed to Pass" & it worked. Then when I got my LS/VTEC (high flow cat) I would only pass 1/3 (or however many tests there are) so I've been turning down the fuel pressure all the way down & it passed 2 times like that now.