Car headers are aftermarket exhaust components that replace the stock exhaust manifold. Their primary job is to efficiently channel hot exhaust gases out of the engine's cylinders. Unlike a stock manifold, which often has restrictive design features to minimize cost and noise, headers are engineered with individual tubes for each cylinder that merge into a larger pipe called a collector. This design significantly reduces exhaust backpressure, the resistance that gases face when exiting the engine.
By minimizing backpressure, headers allow the engine to "breathe" better. This leads to more efficient expulsion of exhaust, which in turn lets the engine draw in a fresh air-fuel mixture more effectively. The result is a noticeable increase in horsepower and torque, particularly in the mid-to-high RPM range. Headers are a foundational modification for performance enthusiasts.
There are several key types of headers:
- Long-Tube Headers: Offer the greatest performance gains by allowing exhaust pulses more time to scavenge gases from other cylinders. They often require significant custom installation.
- Shorty Headers: A more direct replacement for stock manifolds, providing a moderate power increase with easier installation. They are a popular choice for a balance of performance and practicality.
- Headers with Catalytic Converters: Some designs integrate high-flow catalytic converters to maintain emissions compliance, which is crucial for street-driven vehicles.
The performance benefit varies significantly by vehicle and engine type. Generally, engines that are more restrictive from the factory see the biggest gains. The table below summarizes typical performance improvements based on header type and vehicle application.
| Header Type | Vehicle Application | Typical Horsepower Gain | Typical Torque Gain | Key Consideration |
|---|
| Long-Tube | V8 Muscle Car (e.g., Ford Mustang GT) | 15-30 HP | 15-25 lb-ft | May require catalytic converter relocation; can affect ground clearance. |
| Shorty | V6 Sedan (e.g., Honda Accord V6) | 5-12 HP | 5-10 lb-ft | Easier "bolt-on" installation; often maintains factory emissions equipment. |
| Long-Tube | 4-Cylinder Turbo (e.g., Subaru WRX) | 10-20 HP | 10-18 lb-ft | Significant gains when paired with a turbocharger tune; reduces turbo lag. |
| Shorty | Small Displacement Truck (e.g., Toyota Tacoma) | 3-8 HP | 5-9 lb-ft | Modest improvement for low-RPM torque; improves engine response for towing. |
It's important to note that installing headers will change your car's exhaust note, usually making it louder and more aggressive. For maximum performance, headers are often installed as part of a larger "exhaust system" upgrade that may include a high-flow catalytic converter and a performance muffler.
