Aftermarket Headers: More Power for Honda Civic Si Engines

An Introduction to Civic Si Headers

The Honda Civic Si is a sport compact car that has been popular with tuners and performance enthusiasts for decades. One of the most common modifications people make is upgrading the factory exhaust headers. Headers play a crucial role in engine performance by optimizing exhaust flow. Upgrading to aftermarket headers on a Civic Si can unlock hidden horsepower and torque while also enhancing the signature rasp that these cars are known for.

How Do Headers Work?

Headers connect the engine's exhaust ports to the rest of the exhaust system. They funnel the hot exhaust gases towards the catalytic converter and muffler. Headers have a few important jobs:

• Increase exhaust flow and scavenging by equalizing the length of each exhaust runner.
• Improve power by reducing backpressure that restricts exhaust flow.
• Enhance torque curve by tuning the harmonics and pulses of exhaust gas.

The factory Civic Si headers are designed to be inexpensive to manufacture and meet emissions regulations. Aftermarket headers make tradeoffs to maximize power instead.

Benefits of Aftermarket Civic Si Headers

Here are some of the benefits you can expect from upgrading the headers on a Honda Civic Si:

• Increased Horsepower - Aftermarket headers provide freer breathing and less restrictive bends. This reduces pumping losses and backpressure for more usable power.
• Enhanced Torque - Tuning the header design and runner lengths boosts low end torque. This improves acceleration and drivability.
• Weight Savings - High quality aftermarket headers are constructed from stainless steel and titanium. This trims pounds off the factory cast iron units.
• Improved Throttle Response - More immediate spool up and reduced lag improves the connection between the driver's right foot and the tires.
• Signature Tone - Many aftermarket Civic Si headers have a raspy, aggressive exhaust note perfect for performance driving.

Popular Header Brands

There are many reputable manufacturers producing performance headers for the Honda Civic Si including:

• PRL Motorsports - One of the top Civic Si header brands. Their Cobra series offers race-inspired designs.
• Skunk2 - A leader in Honda performance with different header options to suit any build.
• Treadstone - Makes affordable mandrel-bent headers to maximize exhaust flow.
• OBX Racing - Budget-friendly cast stainless headers with catalyzed and non-cat options.
• DC Sports - DC Sports ceramic coated S1 series is a very popular header choice.

Header Style and Design

There are a few key considerations when selecting new headers for your Civic Si:

• Material - Stainless steel is best for durability but titanium offers the most weight savings.
• Coating - Ceramic and high-temp coatings reduce heat transfer and prevent warping.
• Tube Size - Bigger is not always better. Optimal diameter balances velocity and flow rate.
• Catalytic vs Non-Cat - Non-cat headers have better flow but may not be legal in your area.
• Fabrication - Mandrel bends perform better than crush bends in many cases.

Installing Aftermarket Headers

Here is a quick overview of the header install process on a Civic Si:

1. Lift the front of the car and support it safely on jack stands.
2. Disconnect the battery to prevent electrical issues.
3. Remove stock exhaust manifold and exhaust system.
4. Inspect gaskets and replace if needed.
5. Install new headers using high temp gasket sealant.
6. Reconnect oxygen sensors to header collectors.
7. Bolt new exhaust system to headers.
8. Recheck all clamps and hardware.
9. Start the car and check for leaks.

A good set of tools and DIY skills are recommended for this project. An experienced mechanic can complete the installation in 2-3 hours. It's critical to have the engine properly tuned on a dyno after installing new headers to maximize performance gains.

Header Upgrades for Common Civic Si Generations

Let's take a closer look at some of the most popular aftermarket header options for various generations of the Honda Civic Si.

8th Gen Civic Si (2006-2011)

The 8th generation was an exciting Civic Si thanks to the high-revving naturally aspirated VTEC engine. Here are some great header choices:

• PRL Cobra
• Skunk2 Megapower RR
• OBX Racing Stainless Steel
• DC Sports S1

9th Gen Civic Si (2012-2015)

The 9th gen saw the Civic Si switch to more torque-focused power delivery. These headers deliver on 9th gen builds:

• Treadstone TR8
• Hybrid Racing
• PRL Motorsports V2
• RSX Header

10th Gen Civic Si (2017-2021)

This era of turbocharged Civic Si responds very well to header upgrades like:

• PRL Motorsports Race
• Skunk2 Pro Series
• Treadstone TR10
• Full-Race Turbo Manifold

No matter what generation Honda Civic Si you own, quality aftermarket headers represent one of the best bang-for-buck power mods available.

FAQs

Are aftermarket headers worth it?

Absolutely. Aftermarket headers are one of the best performance upgrades available for the money. Headers free up horsepower and torque by reducing restriction and backpressure. The right set of headers can add over 15whp to a Civic Si when combined with proper tuning.

Will headers void my warranty?

Changing exhaust headers can potentially void aspects of the factory powertrain warranty. Always check your owner's manual or consult the dealer to understand warranty restrictions before modifying the vehicle.

Should I get cat or non-cat headers?

This depends on your emissions laws. Non-catalytic converters headers offer the most power but may not be legal. High flow catalytic converters are a good compromise for street driven vehicles. Check your local ordinances to ensure compliance.

How difficult is it to install headers?

Header installation is moderately difficult and will take 2-3 hours for most DIYers. Proper tools, mechanical skills, and patience are required. A professional shop can install headers in 1-2 hours.

Will headers make my car louder?

Headers themselves don't add sound, but they do enhance the tone when paired with a performance exhaust system. Headers provide more airflow which allows the exhaust to be louder and more aggressive sounding.

FAQs

What maintenance is required for headers?

Headers require occasional re-torquing of the bolts to ensure a proper seal over time. Use of high temp anti-seize compound on the bolts is also recommended. Periodic cleaning may be needed to remove built up carbon deposits over time.

Will headers void my engine warranty?

Headers themselves do not void engine warranties, but improper installation or tuning afterwards can potentially void claims. Always use reputable tuners and mechanics when modifying your vehicle.

Do I need a tune with headers?

Yes, it's critical to get your Civic Si properly tuned on a dyno after installing headers. This allows the ECU to adapt to the increased airflow for maximum power gains and drivability.

Can I run headers without a cat?

It depends on emissions laws in your area. Running non-catalytic converter headers may set check engine lights or fail visual inspections. High flow catalytic converters are street-legal options.

Will header wrap protect my engine bay?

Header wrap can reduce under-hood temperatures slightly but is mainly used to protect nearby components. Thermo-Tec, DEI, and other brands offer quality wraps.