Should You Buy High Flow Catalytic Converters?

Catalytic converters reduce engine emissions and became popular in 1975, when the EPA (Environmental Protection Agency) and the US Government released stricter regulations on exhaust emissions. That’s why most US vehicle manufacturers implemented catalytic converters as factory standard equipment that year. Environmental awareness spread globally; in 1992, the Euro I regulation demanded that all vehicles manufactured in Europe must have a catalytic converter.

Although there are still regions where emissions regulations are not so rigorous, it would be accurate to say that in the last 20 years or so, every new car has been fitted with a factory catalytic converter.

How Do Standard Catalytic Converters Affect Engine Performance?

Catalytic converters have an internal mesh generally made of platinum, palladium, and other materials that react with the gasses coming from the engine, transforming them into less contaminating gasses. Standard catalytic converters can be very restrictive depending on the vehicle's age. Over time, carbon builds up over the catalytic converters’ mesh, making them even more restrictive.

Engine failures such as misfires and other problems may help clog the catalytic converter even faster. Some studies claim that modern catalytic converters reduce engine output by only about 3% or less. Although it can sound insignificant for many people, it’s a lot for a car enthusiast who is always looking for engine optimization, and engine tuners know for sure how much work is needed to make an engine gain 3% extra power output. Standard catalytic converters add back pressure to the engine, slowing the exhaust gas speed and preventing the engine from reaching its peak power.

Besides, if you have a tuned or modified engine, a factory catalytic converter will fail to provide your engine with the extra gas flow needed to get the max out from your engine. Whether you have upgraded your exhaust, a standard cat is an undesired bottleneck affecting your high-performance engine.

Why Should I Install a High Flow Catalytic Converter Instead of Just Deleting the Stock Cat?

Removing, gutting, or hollowing a standard catalytic converter may sound tempting. It’s cheap, easy, and it seems straightforward. Some companies sell “test pipes” that replace the catalytic converter for an empty tube. This is illegal in many states and jurisdictions, and the penalty for doing it can be much more expensive than buying a high-flow cat and may include jail time. On top of being harmful to the environment, it may turn your “check engine” light on your instrument cluster. Besides, some cats make the engine sound awful when they are gutted.

Whether you have a stock or a highly tuned engine, buying a good high-flow catalytic converter is always the best choice instead of deleting the stock cat. Your engine will gain some HP (the amount depends on the engine’s displacement, type, and tuning level), and it will still pass the emission tests. Your “check engine light” will stay off, and your exhaust will sound awesome and you won’t have to deal with the nauseating exhaust fumes that you would have without a catalytic converter.

Most turbocharged engines have their catalytic converters integrated into their downpipes. If you want to upgrade your downpipe and keep your vehicle street-legal, you should buy a downpipe with a high-flow catalytic converter.

Benefits of High Flow Catalytic Converters

To summarize, the benefits of high flow catalytic converters are:

Increased Engine Power

Depending on your vehicle’s model and make, your engine tuning level, and other numerous factors, your engine power will be increased. The result can vary a lot depending on these factors. As a thumb rule, high-flow cats are a must for heavily tuned engines and old (pre-1995) sports cars with primitive stock catalytic converters. Turbocharged engines should use high-flow cats when they get improved turbo downpipes. If you own a standard car with no significant modifications, there are many things that you can improve before touching the catalytic converter.

Better MPG

Fuel economy is probably the least important thing for owners of heavily modified engines. However, it’s good to note that high-flow catalytic converters increase engines’ MPG. At the same RPMs, engines with better exhaust flow need to burn less fuel than engines with restricted airflow.

Restored Engine Power

If you own an old vehicle and your cat is clogged, it is always better to invest a little more money in a good quality high-flow catalytic converter than to buy a cheap stock replacement cat. You will save money in the long run, your vehicle will run better, and the high-flow cat will last for the remainder of your vehicle's life.