Choosing the correct exhaust pipe diameter is one of the most important decisions in any custom exhaust build. Too small, and you restrict flow and lose power. Too large, and you sacrifice low-end torque and throttle response.
This guide covers the full range of diameters available at RF Distributors and helps you match the right size to your engine and application.
What Diameters Are Available?
We stock stainless steel exhaust components from 32mm to 127mm in both 201 and 304 grade stainless steel. This range covers everything from small-bore headers on naturally aspirated four-cylinder engines to large-diameter systems on turbocharged V8 builds.
Small Bore: 32mm – 45mm
These sizes are commonly used for header primaries, small-capacity engines, and motorcycle applications. At RF Distributors, we carry bends, straight pipe, and flex pipe in 32mm, 35mm, 38mm, 40mm, 42mm, and 45mm.
Mid Range: 51mm – 70mm
The most popular range for passenger vehicles and light performance builds. A 51mm (2-inch) system suits most naturally aspirated four-cylinder engines, while 57mm and 63mm are ideal for turbocharged four-cylinders and naturally aspirated six-cylinder engines.
Large Bore: 76mm – 101mm
This range is designed for high-output engines. 76mm (3-inch) is the go-to for most turbocharged builds and performance V6 engines. 89mm and 101mm systems are used on V8 engines and heavily modified turbocharged setups where maximum exhaust flow is critical.
Extra Large: 114mm – 127mm
These sizes are reserved for serious performance applications — large-displacement turbocharged engines, truck exhausts, and industrial applications. We stock both 1.5mm and 2mm wall thickness bends in these sizes for added durability.
How to Choose the Right Diameter
The general rule is to match your exhaust diameter to your engine output:
| Engine Output | Recommended Diameter |
|---|---|
| Up to 110kW | 45mm – 51mm |
| 110kW – 190kW | 57mm – 63mm |
| 190kW – 300kW | 63mm – 76mm |
| 300kW – 450kW | 76mm – 89mm |
| 450kW+ | 89mm – 127mm |
These are guidelines — factors like turbocharging, exhaust length, and intended use all play a role. When in doubt, contact us for advice tailored to your specific build.
Available Across All Product Types
Whatever diameter you choose, RF Distributors stocks matching components across our full range — bends, straight pipe, flex pipe, reducers, V-band clamps, and joint clamps. This makes it easy to build a complete system from a single supplier with consistent sizing throughout.
