Pros and Cons of High Flow Cats

High flow catalytic converters, often referred to as high flow cats, have gained popularity among automotive enthusiasts. These aftermarket exhaust components aim to improve vehicle performance while still complying with emission standards. This article explores the pros and cons of high flow cats to help you make an informed decision.

What Are High Flow Cats?

High flow cats are catalytic converters designed to enhance exhaust flow compared to their stock counterparts. They are typically less restrictive, allowing for improved engine performance. High flow cats achieve this by using advanced catalyst materials and innovative designs that minimize exhaust gas backpressure.

Pros and Cons of High Flow Cats

Pros of High Flow Cats

High flow cats offer several advantages over traditional catalytic converters. Here are some of the pros of high flow cats:

Improved Performance

One of the significant advantages of high flow cats is the potential for improved performance. By reducing exhaust backpressure, these catalytic converters allow the engine to breathe more freely.

This increased airflow can result in enhanced horsepower and torque, providing a noticeable boost to overall performance.

Enhanced Exhaust Sound

High flow cats can also contribute to a more aggressive exhaust sound. Due to their less restrictive design, these converters allow for a deeper and louder exhaust note.

This added aural presence can enhance the driving experience, especially for automotive enthusiasts seeking a more engaging sound from their vehicles.

Compliance with Emissions Regulations

While high flow cats are designed to reduce exhaust restrictions and improve performance, they still maintain the ability to effectively reduce harmful emissions.

They feature a catalyst coating that helps convert harmful pollutants, such as carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC), into less harmful substances. This ensures that the vehicle remains compliant with emissions regulations while offering improved performance.

Durability and Longevity

High flow cats are often constructed using high-quality materials that are more durable and resistant to heat and corrosion compared to standard catalytic converters. This ensures a longer lifespan and reduces the chances of premature failure.

Additionally, some high flow cats are backed by warranties, providing further peace of mind to the vehicle owner.

Read: How to Fix an Overheating Engine While Idling

Cons of High Flow Cats

While high flow catalytic converters offer several advantages, there are also some potential drawbacks to consider. Here are a few cons of high flow cats:

Higher Cost

One of the drawbacks of high flow cats is their higher cost compared to stock catalytic converters. The advanced materials and designs used in their construction contribute to the increased price tag.

This additional investment may not be justifiable for all vehicle owners, particularly those on a tight budget or those who prioritize cost-effectiveness over performance enhancements.

Potential Check Engine Light Issues

High flow cats may sometimes trigger a Check Engine Light (CEL) due to their reduced catalytic efficiency. While modern engine management systems can often adapt to these changes, it’s not uncommon for some vehicles to experience CEL illumination. This issue might require additional modifications or tuning to rectify, adding complexity and cost to the overall installation.

Legal Compliance

It’s crucial to consider the legal aspect before installing high flow cats. Depending on your region, aftermarket catalytic converters may not be street legal or may require specific certifications. It’s essential to research and ensure that the high flow cats you choose comply with local emissions regulations to avoid potential legal issues.

Potential Warranty Issues

Modifying the catalytic converter system, including the installation of high flow cats, can void the manufacturer’s warranty. If any issues arise in the vehicle’s exhaust system or related components, the warranty coverage may be invalidated. It’s important to consider the potential impact on warranty coverage before making any modifications.

High Flow Cats Vs Stock Catalytic Converters

When comparing high flow catalytic converters (high flow cats) to stock catalytic converters, there are several factors to consider. Here’s a comparison between the two:

Performance Comparison

When comparing high flow cats to stock catalytic converters, the performance difference can vary depending on the vehicle and its modifications.

In general, high flow cats offer improved performance, but the extent of these gains will differ from one vehicle to another. Factors such as engine size, modifications, and tuning play a significant role in determining the actual performance increase.

Emissions Comparison

Stock catalytic converters are specifically designed to meet strict emission standards and minimize harmful pollutants. High flow cats, while still meeting emissions requirements, may not be as efficient in reducing emissions as their stock counterparts.

However, they strike a balance between performance and emissions, making them a suitable choice for many car enthusiasts.


High flow cats can contribute to a more aggressive and sporty exhaust sound. The improved flow characteristics and reduced restriction can result in a deeper tone and increased volume. Stock catalytic converters, being more restrictive, may produce a quieter and more subdued exhaust note.


High flow catalytic converters are often more expensive than stock catalytic converters. The improved design, higher-quality materials, and enhanced performance come at an added cost. Stock catalytic converters are typically more cost-effective, as they are mass-produced and widely available.


Are high flow cats worth it?

High flow cats can be worth it for automotive enthusiasts seeking improved performance and a more aggressive exhaust sound. However, it’s essential to consider the associated costs, potential check engine light issues, and legal compliance requirements.

Do high flow cats increase horsepower?

High flow cats can contribute to increased horsepower by reducing exhaust backpressure and allowing the engine to breathe more freely. The extent of the horsepower gains will vary depending on the vehicle and its modifications.

Will high flow cats pass emissions testing?

High flow cats are designed to meet emissions requirements, although they may not be as efficient as stock catalytic converters in reducing emissions. It’s crucial to ensure that the high flow cats you choose comply with local emissions regulations to pass emissions testing.

Can high flow cats be installed on any vehicle?

High flow cats can be installed on various vehicles, but it’s important to consider the vehicle’s modifications and local emissions regulations. Assessing your specific situation will help determine if high flow cats are compatible and compliant with your vehicle.