What are Headers? | Revv.ly Glossary

What are Headers?

Rev the engine hard, feel it climb through the power band, and listen--really listen--to the difference headers make. That raspy, aggressive bark replacing the muffled stock tone. That's the sound of exhaust gases flowing freely, no longer fighting restrictive factory manifolds. And if you're driving a naturally aspirated car, those headers aren't just making noise--they're unlocking power that was always there, waiting.
Headers replace the factory exhaust manifolds, and they do so with a specific purpose: optimize exhaust flow by tuning the length and diameter of each primary tube. Factory manifolds are designed for cost, packaging, and emissions. Performance headers are designed for power, and the difference is immediately audible.

The Design Philosophy

Factory exhaust manifolds often look like afterthoughts--cast iron or stamped steel lumps that gather exhaust from multiple cylinders and merge them with minimal regard for flow dynamics. Headers take a different approach:
Individual Primary Tubes -- Each cylinder gets its own tube of specific length and diameter. This allows tuning for exhaust pulse timing--when done right, the exhaust pulse from one cylinder helps scavenge exhaust from the next.
Merge Collectors -- Where tubes come together matters. Quality headers use collectors designed to maintain flow momentum and manage pulse interaction.
Equal-Length vs. Unequal-Length -- Equal-length primaries deliver consistent exhaust pulses and smoother power delivery. Unequal-length (as on Subaru boxer engines) create that distinctive burble but with potentially less optimal scavenging.

The Types

Long-Tube Headers -- Extend past the catalytic converters (or position high-flow cats in the system). Maximum power potential, particularly in the mid-range and top end where the tuned length optimizes scavenging. On naturally aspirated V8s, long-tubes can add 20-40+ horsepower. They also make installation challenging and often require exhaust system modifications.
Short-Tube (Shorty) Headers -- Replace the manifold but connect to the factory catalytic converters. Easier installation, more modest gains, usually emissions-legal. Think of them as a compromise between factory and full long-tubes.
Tri-Y Headers -- Pair primaries together before merging pairs, creating a stepped merge. The design can broaden the power band, offering benefits across a wider RPM range than traditional 4-into-1 designs.

The Application Matters

Naturally Aspirated Engines -- Headers make the biggest difference here. Without a turbo or supercharger dictating exhaust flow, the header design directly affects volumetric efficiency. NA engines respond remarkably well to quality headers.
Turbocharged Engines -- The turbo dominates exhaust flow dynamics. Headers for turbo applications focus on feeding the turbine efficiently rather than scavenging. Gains are more modest, and on many platforms, a downpipe upgrade delivers more benefit.
High-RPM Engines -- Engines that make power up high benefit most from header tuning. A Honda S2000 or E46 M3 with headers transforms the top-end experience.

The Installation Reality

Headers aren't always simple to install:

• Heat Management -- Headers get extremely hot. Heat wrap or ceramic coating helps, but heat management requires consideration.
• Clearance Issues -- Long-tube headers on some vehicles create clearance problems with steering, suspension, or floor pans.
• O2 Sensor Placement -- Emissions-controlled vehicles need O2 sensors in specific locations. Aftermarket headers may require spacers or tuning to avoid check engine lights.
• Ground Clearance -- Some headers position collectors lower than stock, creating scraping potential on lowered cars.
  Professional installation is worth considering unless you're experienced with exhaust work.

The Experience

Driving a properly header-equipped car changes the experience. The engine breathes easier, responses feel crisper, and the sound--that beautiful, uncorked sound--reminds you with every throttle input that you've improved on the factory's compromises.
Share your header experiences on Revvly--the community that appreciates the music of a well-built exhaust.
Related: Downpipe, Tune, Intake Manifold
Headers Transform These Platforms: Honda S2000, Ford Mustang GT, Subaru BRZ/Toyota 86