High Performance Headers EXT491 — Holden Torana LH LX 350–383 Small Block Chev

The EXT491 high performance exhaust headers are engineered for Holden Torana LH and LX models running high-performance 350 or 383 Small Block Chev (SBC) V8 engines. Designed as an interference-style system, these headers are suited to modified engines producing strong mid-to-high RPM power.

Vehicle Compatibility

• Holden Torana LH
• Holden Torana LX
• Engine: 350 SBC
• Engine: 383 Stroker SBC

Header Design

• Interference design for modified high performance engines
• Optimised for high-flow cylinder heads and larger camshaft combinations
• Mandrel bent for consistent internal diameter
• Precision formed collectors for smooth gas transition

Pipe Specifications

• Primary Pipes: 1.75"
• Secondary Pipes: 2.25"
• Collector Outlet: 3.00"

Why Good Headers and Exhaust Systems Matter

On average, a 5.7L (350ci) Small Block Chev engine draws ~11,400 L of air per minute and expels ~34,200 L per minute at 4000rpm [@600°C]

At 5000rpm, a well-built 350 SBC engine draws ~14,250 L of air per minute and expels ~42,750 L per minute [@600°C]

A 383 stroker increases displacement and airflow demand further, requiring efficient primary and collector sizing to maintain exhaust velocity and support high-RPM scavenging. The 1.75" primary and 2.25" secondary combination feeds into a 3.00" collector, allowing strong cylinder evacuation and improved top-end horsepower while maintaining mid-range torque.

Gaskets

Recommended gasket: DSF009

Important Notes

• Made to Order 6-8 week [approx] 
• Not suited to raised port cylinder heads
• Vehicle modifications may be required
• Professional installation recommended
• Remote oil filter recommended
• Not suited to 6.0L engine sump

What’s Included

• 1 x Custom SBC Headers EXT491

Customer Support

For phone orders, advice, or part enquiries – contact us:

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87A Planthurst Road, Carlton NSW 2218, Australia
Exhaust Systems Since 1983