I'm not an expert but doesn't "no decat" mean your exhaust doesn't have one of the catalytic converters that normal exhaults have to remove emissions - the no decat pipes are performance parts to increase performance by removing the restriction of the converter from exhaust. As far as I know you would NOT want to got to NCT centre with one of these performance exhausts - replace with normal cat exhaust first and then swap back after. That's what i was thinking i would have to do if i got one of those "race" exhausts...