1999–2006 Chevy and GMC GMT800 V8 Exhaust Headers
Replace restrictive factory-style exhaust manifolds with a smoother-flowing header layout and a more pronounced V8 exhaust character. This FLASHARK exhaust header is designed for listed Chevrolet and GMC GMT800 applications equipped with 4.8L, 5.3L or 6.0L V8 engines and uses a mirror-polished 201 stainless steel construction.
This configuration is identified as the EGR-valve version. Match the vehicle year, model, engine, drivetrain and factory EGR layout before ordering. Existing exhaust modifications can change outlet alignment and the work required to connect the headers to the rest of the exhaust system.
Specifications
| Brand | FLASHARK |
|---|---|
| SKU | FLES08203 |
| Product Model | EH28136 |
| Product Type | V8 exhaust header with EGR-valve configuration |
| Material | 201 stainless steel |
| Finish | Mirror polished |
| Manifold-Port Measurement | 1.875 inches, eight ports |
| Header Outlet | 2.5-inch outside diameter |
| Main Piping Diameter | 2.5 inches |
| Engine Platform | Listed GMT800 4.8L, 5.3L and 6.0L V8 applications |
Key Features
- Smoother exhaust path: Separate header runners help exhaust gases leave each cylinder with less interference than a shared cast-iron manifold layout.
- Natural V8 sound: The header layout can produce a deeper, clearer exhaust note. Final volume and tone depend on the catalytic converters, Y-pipe, muffler and cat-back system.
- Stainless steel construction: The 201 stainless steel tubing uses a mirror-polished finish for a clean appearance.
- EGR-version configuration: Intended for listed applications that require the corresponding factory EGR layout.
- Defined outlet size: The 2.5-inch outside-diameter outlet provides a reference point when planning the downstream exhaust connection.
GMT800 Header Installation, Review & Sound Videos
See the header installation process, component layout and finished exhaust sound on GMT800 Chevrolet and GMC V8 applications.
Silverado 5.3L Installation: A closer look at the header installation process and the completed setup.
GMT800 Installation & Review: An owner review covering Flashark stainless headers and a cold air intake installation.
Installation, Review & Sound Test: A real-vehicle walkthrough showing the installation and resulting exhaust tone.
Built for Better Flow and Sound
Factory cast-iron manifolds collect several exhaust pulses into a compact passage. A tubular header gives the cylinders separate runners before the exhaust streams merge, supporting smoother exhaust movement and a more distinct exhaust note.
Throttle response, torque delivery and upper-rpm pull depend on the complete vehicle setup, including engine condition, header sealing, downstream exhaust, catalytic-converter configuration and calibration. Proper installation and a leak-free connection are essential to obtaining a consistent result.
Factory Manifold vs. Tubular Header
| Area | Factory-Style Manifold | FLASHARK Header |
|---|---|---|
| Exhaust path | Compact shared collector | Separate tubular runners before the merge point |
| Material | Commonly cast iron | 201 stainless steel |
| Sound character | More subdued at the cylinder head | Exhaust pulses may sound deeper and more defined |
| Installation planning | Matches the factory exhaust layout | Requires clearance and downstream-connection checks |
Installation Notes
Technician note: Header installation involves high-temperature exhaust joints and limited working space around the engine and drivetrain. Professional installation is recommended when fabrication, seized fasteners or downstream exhaust changes are involved.
- Allow the engine and exhaust system to cool completely before work begins.
- Inspect the cylinder-head sealing surfaces and correct damaged threads before fitting the headers.
- Keep spark-plug wires, wiring, hoses and cooler lines away from the header tubes.
- Check steering, transmission, driveline and chassis clearance before final tightening.
- Align the downstream exhaust without forcing the header outlets sideways or upward.
- Start the engine and inspect every flange and connection for exhaust leaks.
- Recheck accessible fasteners after the first complete heat cycles.
Who This Header Is For
This header is intended for owners of the listed Chevrolet Silverado 1500, GMC Sierra 1500 and Chevrolet Avalanche 1500 applications who want a tubular exhaust-header layout, a stronger V8 exhaust character and a platform for additional exhaust-system work.
It is not the right choice for a vehicle that falls outside the listed fitment, uses a different factory EGR layout, requires a fully documented emissions-compliant replacement, or must retain an unchanged factory downstream exhaust connection.
Emissions & Street-Use Notice
Exhaust modifications can affect catalytic-converter placement, oxygen-sensor operation, diagnostic codes and local emissions compliance. Check the vehicle configuration and applicable regulations before installation. No check-engine-light or road-use guarantee is provided.
Related GMT800 Exhaust and Intake Options
Browse additional FLASHARK exhaust headers for different header layouts and listed applications. Owners planning a broader GMT800 airflow upgrade can also compare the 1999–2006 Chevy and GMC Vortec cold air intake. Check each product’s fitment and selected configuration separately.
Shipping & Returns
Free U.S. Shipping: Orders are typically processed within 1–2 business days and delivered within 7–9 business days. Additional charges may apply to remote areas.
30-Day Returns: Unopened and unused items in their original packaging may be returned within 30 days of receipt. Return shipping is covered for verified quality issues.
Worry-Free Delivery: Optional protection against eligible loss, theft, delay, or transit damage is available at checkout.
Fitment & Compatibility
✅ Verified Fitment
| Brand | Model | Year Range | Full Compatible Specs |
|---|---|---|---|
| Chevrolet | Silverado 1500 | 1999-2006 | 4.8L, 5.3L, 6.0L V8 Engine |
| GMC | Sierra 1500 | 1999-2006 | 4.8L/5.3L/6.0L V8 Engine |
| Chevrolet | Avalanche 1500 | 2002-2006 | 4.8L/5.3L/6.0L V8 Engine |
- Check the factory EGR configuration against the selected EGR-valve header version.
- Check whether the vehicle is 2WD or 4WD before installation.
- Inspect the transmission, front driveline, cooler-line and chassis clearance around the header path.
- Compare the 2.5-inch header outlet with the existing Y-pipe or downstream exhaust connection.
- Previously modified exhaust systems may require additional alignment or fabrication.
- Use the vehicle selector or contact customer support when the exact configuration is unclear.
1999–2006 Chevy and GMC GMT800 Exhaust Header FAQs
Q1: Which vehicles are listed for this exhaust header?
A1: The detailed fitment includes 1999–2006 Chevrolet Silverado 1500, 1999–2006 GMC Sierra 1500 and 2002–2006 Chevrolet Avalanche 1500 applications with listed 4.8L, 5.3L or 6.0L V8 engines.
Q2: How should I check fitment for a Tahoe, Suburban or Yukon?
A2: Use the vehicle selector with the exact year, model, engine and drivetrain. Contact customer support with the VIN or full vehicle configuration when the required application is not shown in the detailed fitment table.
Q3: Will these headers fit both 2WD and 4WD trucks?
A3: Drivetrain layout can change front-driveshaft, differential and chassis clearance. Match the drivetrain in the vehicle selector and inspect the header path before installation.
Q4: What does the EGR-valve version mean?
A4: This configuration is identified for vehicles using the corresponding factory EGR layout. Compare the factory manifold and EGR connection with the selected header before removing the original parts.
Q5: Will the header connect to the factory Y-pipe?
A5: The header outlet is listed as 2.5 inches outside diameter. Connection requirements depend on the existing Y-pipe and any previous exhaust modifications. Matching exhaust work or fabrication can be required.
Q6: Is an ECU or PCM tune required?
A6: Calibration requirements depend on the complete exhaust configuration and how the oxygen sensors and emissions equipment are retained. Read diagnostic codes after installation and consult a qualified tuner when the exhaust layout changes sensor behavior.
Q7: Can the headers cause a check-engine light?
A7: An exhaust leak, oxygen-sensor issue or change to emissions equipment can trigger a diagnostic code. A header installation alone should never be presented as a guaranteed CEL-free modification.
Q8: How will the exhaust sound change?
A8: Tubular headers can make the V8 exhaust pulses sound deeper and more defined. Overall volume, drone and rasp depend mainly on the catalytic converters, Y-pipe, muffler, resonators and cat-back system.
Q9: How much horsepower will the headers add?
A9: Results depend on engine condition, downstream exhaust, catalytic-converter layout, calibration and installation quality. The product should be evaluated as one part of the complete exhaust system rather than as a guaranteed standalone power figure.
Q10: What should I inspect before installation?
A10: Check the cylinder-head surfaces, factory EGR layout, spark-plug wires, oxygen-sensor routing, cooler lines, steering, drivetrain clearance and downstream exhaust connection.
Q11: Can I install these headers at home?
A11: Experienced DIY owners may perform the work with suitable lifting equipment and exhaust tools. Professional installation is recommended when fasteners are seized, clearance is limited or the downstream exhaust requires fabrication.
Q12: How can I reduce the risk of an exhaust leak?
A12: Clean the sealing surfaces, align the exhaust without placing side load on the outlets, tighten the fasteners evenly and recheck accessible connections after the first heat cycles.
Q13: Are these headers street legal?
A13: Street-use and emissions requirements vary by location and vehicle configuration. Check local regulations before modifying catalytic converters, oxygen-sensor placement or other emissions equipment.
Q14: Who should not buy this header?
A14: Do not order when the vehicle is outside the listed fitment, uses a different EGR layout, must retain an unchanged factory exhaust connection or requires a specifically certified emissions-compliant replacement.