Silverado & Sierra 1 7/8" Longtube Headers | 1999-2006 — Manufacturer part number: 25-1011.

(IN STOCK)

Speed Engineering Silverado & Sierra longtube headers are made out of 304 stainless steel and offer great quality, performance, and affordability. Our Silverado & Sierra longtube headers are mandrel bent, tig welded, and feature natural stainless steel construction. All of our Silverado & Sierra longtube headers have been dyno proven. We stand behind our Silverado & Sierra longtube headers in saying you will not find a better fitting, quality built, budget header for your vehicle.

Features include:

• Mandrel Bent Tubing
• Race Version with "NO" Air & EGR Fittings
• Full 1 7/8" Primaries
• 3" Collector
• Longtube Header Design
• Silverado / Sierra / SUV LS Headers
• Gains over 25+ rwhp
• V8 Engines Only
• 4.8L, 5.3L, 6.0L Engines
• CNC Machined Flanges
• Natural 304 Stainless Steel
  
• Standard Graphite Manifold Gaskets

Vehicle Applications:

• 1999-2006 Chevrolet  SIlverado Truck & Tahoe SUV (2wd & 4wd)
  
• 1999-2006 GMC Sierra Truck &  Yukon SUV (2wd & 4wd)
  
• 2002-2006 Cadillac EXT Truck (2wd & 4wd)
  
• 2002-2006 Cadillac Escalade SUV (2wd & 4wd)
• 2002-2006 Chevrolet Avalanche (2wd & 4wd)

Note: If using a larger 4L80E transmission the bellhousing ears may need to be trimmed for proper clearance.

Note: Earlier 2500's might have fitment issues due to chassis being designed from previous years. Earlier years have the upper control arms mounted on top of the chassis, which would cause fitment issues.

Note: Most 6.0 applications have a 2 into 1 exhaust system which our y pipe system will not work with. Double check your exhaust for confirmation of fitment with single exhaust. Our x pipe kit can work on the 2 into 1 exhaust systems, but require fabrication for connection.

(Warning) This is a RACE ONLY product manufactured and sold for installation on vehicles to be used solely for competition purposes. Once this part is installed, the vehicle may never be used, or registered or licensed for use, on a public road or highway. If you install this part on your vehicle and use the vehicle on a public road or highway, you will violate the Clean Air Act 203(a)(3), 42 U.S.C, 7522(a)(3) and may be subject to personal civil or criminal liability.

Fitment and ordering

Confirm the vehicle, engine, dimensions and application restrictions listed above before ordering. Speed Engineering parts are designed to work with Speed Engineering components; mixing brands may require modifications.

Available upgrades and related Speed Engineering parts

Use the selectors above to include upgrades with this product. The links below are for reference or separate purchases; do not also buy an upgrade separately if you have already selected it above. Check quantities, included parts, and fitment.

• LS Multi-Layer Steel Gaskets
• Standard Zinc Bolts - LS
• "RED" 10" Total Length Wires
• "RED" 12" Total Length Wires
• "BLACK" 10" Total Length Wires
• "BLACK" 12" Total Length Wires
• Spark Plug Wire Fire Sleeves

Manufacturer specifications and availability checked October 4, 2026. Availability refers to the manufacturer and can change; it does not indicate stock held at Speedzone.

Returns: All Speed Engineering product sales are final. No returns are accepted on Speed Engineering products. Please verify fitment before ordering. See our Return Policy for additional terms. This does not limit any consumer rights that cannot be waived under applicable law.