Do aftermarket catalytic converters work?
On One Hand: Power Gain Is MinimalMost car catalytic converters are barely adequate for stock engines and can often support little more than stock power output. Depending on how well your stock converter flows, power gained from an aftermarket converter install may be fairly minimal.On the Other: They May Be IllegalAlthough all aftermarket high-flow converters are essentially over-sized stock units (with federally mandated internals), not all meet the emissions standards of every state. While most states permit replacement of the converter, California almost certainly will not permit replacement of the converter with anything but a state-approved stock replacement, and only then if your stock converter is missing or damaged.Bottom LineHigh-flow catalytic converters can add horsepower and fuel efficiency to almost any car, but caution is advised in areas where emissions testing is rigidly enforced.
