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High Flow Cats vs Stock Cats: What’s Best for the C8 Corvette?

The mid-engine C8 Corvette offers exhilarating performance straight from the factory, but many owners are hungry for even more power. One popular modification is to install high flow catalytic converters in place of the restrictive stock cats. But is this upgrade worth it for the C8 Corvette? This article will compare high flow cats against stock cats to help C8 owners decide which is best for their needs.

What Are Catalytic Converters?

Catalytic converters are emissions control devices that convert toxic exhaust gases like hydrocarbons, carbon monoxide and nitrogen oxides into less harmful compounds like carbon dioxide, nitrogen and water vapor. They work through a chemical process triggered by a structure inside the converter containing palladium, platinum and rhodium.

All vehicles sold in the United States since 1975 have utilized catalytic converters to comply with emissions regulations. The C8 Corvette uses one high-flow cat and one main cat to clean up its exhaust gases.

Drawbacks of the C8’s Stock Catalytic Converters

While essential for emissions compliance, the C8’s stock catalytic converters do restrict exhaust flow. The main cat in particular creates significant backpressure, robbing the 6.2L LT2 V8 engine of power.

Many C8 owners are installing high flow catalytic converters to unleash more horsepower and torque from their mid-engine machines. When paired with a cat-back exhaust system, high flow cats can allow the LT2 engine to breathe and rev more freely to produce more power.

Benefits of High Flow Catalytic Converters

High flow cats offer larger exhaust passages and increased flow compared to restrictive stock converters. Popular options like the Corsa Xtreme and Borla high flow cats can reduce backpressure by up to 50% compared to stock converters.

Opening up the exhaust system with high flow cats provides these significant benefits for C8 Corvette owners:

  • Increased horsepower and torque output – High flowing cats reduce restrictions for easier breathing.
  • Improved throttle response – Less backpressure means throttle inputs are reacted to more quickly.
  • Enhanced sound – Higher flowing exhaust results in a more aggressive exhaust note.
  • High flow cat compatibility – Works seamlessly with aftermarket exhaust systems.

While power gains from just installing high flow catalytic converters will be modest, additional exhaust modifications like headers and cat-back exhausts can unlock the full potential of the LT2 engine.

Here’s a great video that shows you the differences in the cells that make up catalytic converters. This video does not show C8 cats, but the concept is the same:

Potential Drawbacks of Switching to High Flow Cats

Before installing high flow cats, C8 owners should be aware of a few potential drawbacks:

  • Check engine lights – Swapping cats could trigger check engine light (also commonly referred to as CEL) error codes unless the O2 sensors are adjusted.
  • Increased emissions – High flow cats may allow more harmful gases through versus stock converters.
  • Cost – Quality high flow cats represent a significant expense, ranging from $1,000 to $1,500.
  • Installation challenges – Stock cats can be difficult to remove in the tight confines of the C8 engine bay.

Fortunately, most tuners can adjust for O2 sensor issues, and race-only high flow cats have less stringent requirements for emissions. Cost and installation remain barriers of entry however.

Check Your State Emissions Laws Before Replacing Stock C8 Cats

Before upgrading to high flow catalytic converters, it is critical that C8 Corvette owners check their state laws and emissions testing regulations. While a high-flow cat swap may deliver worthwhile power gains, it could also result in fines or difficulty passing emissions testing in states with stricter regulations. Some states prohibit removing or altering stock catalytic converters, while others prohibit the sale of high-flow race cats that skip stringent CARB requirements. Research your state’s emissions laws thoroughly before diving into installing aftermarket high flow converters.

Additionally, be prepared to reinstall stock catalytic converters if required for emissions testing purposes. Ignoring state laws surrounding catalytic converters can negatively impact the street legality and resale value of modified Corvettes. Doing diligent research beforehand ensures your high performance C8 stays on the right side of the law.

The Verdict: Are High Flow Cats Worth It for the C8 Corvette?

For many C8 owners, the power-building potential of high flow catalytic converters makes them an appealing upgrade. When included as part of a full exhaust system upgrade, they can allow the LT2 engine to really spread its wings and produce intoxicating power gains.

However, keeping expectations realistic is important – a basic cat swap alone may only deliver modest improvements. Further exhaust mods would be needed to fully unlock the performance potential of the C8 with high flow converters installed.

As with any vehicle modification, each C8 owner needs to weigh the pros and cons against their budget and needs. But for dedicated enthusiasts chasing every last horsepower from the capable LT2 small block V8, upgrading to high flow catalytic converters can be a crucial piece of that puzzle.

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