The factory exhaust manifolds on your GMT800 Silverado, Sierra, or full-size SUV are one of the first restrictions holding back your LS engine. This complete full kit pairs Speed Engineering's 1-7/8" longtube headers with a 3" off-road Y-pipe that connects directly to the existing cat-back location — replacing the restrictive factory exhaust manifolds and mid-pipes with a free-flowing stainless system designed for significant horsepower gains, an aggressive exhaust tone, and long-lasting durability. Race version — no air or EGR fittings. Dyno proven to deliver over 25 rear-wheel horsepower over stock.
Built from 304 natural stainless steel with mandrel-bent primary tubes, merge spikes, CNC-machined flanges, and full TIG-welded construction.
⚠️ Important Notes:
- Rear downstream O₂ sensors are not used — a check engine light for catalyst efficiency will appear and must be disabled via PCM tuning
- Most 6.0L applications use a 2-into-1 exhaust system — this Y-pipe kit will NOT work with that configuration. Verify your exhaust has a single (not 2-into-1) configuration before ordering. The Speed Engineering X-pipe kit can work with 2-into-1 systems but requires fabrication for connection
- 4L80E transmission: Bellhousing ears may need to be trimmed for proper clearance
- Earlier 2500-series trucks may have fitment issues — earlier years have upper control arms mounted on top of the chassis, which can cause header clearance problems
Kit Includes:
- 1 Pair of 1-7/8" Stainless Longtube Headers
- 1 Three-inch Off-Road Y-Pipe / Connection Pipe
- 1 Set of Zinc-Coated Header Bolts (upgrade to stainless ARP bolts available at checkout)
- 2 MLS Exhaust Gaskets
Optional: Speed Engineering LS Spark Plug Wires and Plug Wire Fire Sleeves can be added at the time of purchase.
Features:
- Full 1-7/8" Primary Tubes with Merge Spikes — Full-diameter flow from cylinder head to collector for maximum exhaust scavenging
- 3" Collector — Optimized for strong low-to-mid RPM torque
- Race Version — No Air or EGR Fittings
- Mandrel Bent Tubing — Consistent tube diameter through every bend; no crimping, no restriction
- CNC Machined Flanges — Precision fit at the head and collector for a leak-free seal
- 304 Natural Stainless Steel Construction — Corrosion resistant, heat tolerant, and built to last
- Longtube Header Design — Maximum scavenging efficiency vs. shorty or mid-length headers
- Standard Graphite Manifold Gaskets Included
- Dyno Proven — 25+ RWHP gain on 4.8L, 5.3L, and 6.0L applications
- Compatible with 4.8L, 5.3L, and 6.0L V8 Engines
- V8 Engines Only
Vehicle Applications:
Chevrolet Silverado 1500 Truck (2WD/4WD)
- 1999 Chevrolet Silverado 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2000 Chevrolet Silverado 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2001 Chevrolet Silverado 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2002 Chevrolet Silverado 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2003 Chevrolet Silverado 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2004 Chevrolet Silverado 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2005 Chevrolet Silverado 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2006 Chevrolet Silverado 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
GMC Sierra 1500 Truck (2WD/4WD)
- 1999 GMC Sierra 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2000 GMC Sierra 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2001 GMC Sierra 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2002 GMC Sierra 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2003 GMC Sierra 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2004 GMC Sierra 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2005 GMC Sierra 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
- 2006 GMC Sierra 1500 (2WD/4WD) — 4.8L/5.3L/6.0L
Chevrolet Tahoe SUV (2WD/4WD)
- 1999 Chevrolet Tahoe (2WD/4WD)
- 2000 Chevrolet Tahoe (2WD/4WD)
- 2001 Chevrolet Tahoe (2WD/4WD)
- 2002 Chevrolet Tahoe (2WD/4WD)
- 2003 Chevrolet Tahoe (2WD/4WD)
- 2004 Chevrolet Tahoe (2WD/4WD)
- 2005 Chevrolet Tahoe (2WD/4WD)
- 2006 Chevrolet Tahoe (2WD/4WD)
GMC Yukon SUV (2WD/4WD)
- 1999 GMC Yukon (2WD/4WD)
- 2000 GMC Yukon (2WD/4WD)
- 2001 GMC Yukon (2WD/4WD)
- 2002 GMC Yukon (2WD/4WD)
- 2003 GMC Yukon (2WD/4WD)
- 2004 GMC Yukon (2WD/4WD)
- 2005 GMC Yukon (2WD/4WD)
- 2006 GMC Yukon (2WD/4WD)
Cadillac Escalade SUV (2WD/4WD)
- 2002 Cadillac Escalade (2WD/4WD)
- 2003 Cadillac Escalade (2WD/4WD)
- 2004 Cadillac Escalade (2WD/4WD)
- 2005 Cadillac Escalade (2WD/4WD)
- 2006 Cadillac Escalade (2WD/4WD)
Cadillac Escalade EXT Truck (2WD/4WD)
- 2002 Cadillac Escalade EXT (2WD/4WD)
- 2003 Cadillac Escalade EXT (2WD/4WD)
- 2004 Cadillac Escalade EXT (2WD/4WD)
- 2005 Cadillac Escalade EXT (2WD/4WD)
- 2006 Cadillac Escalade EXT (2WD/4WD)
Chevrolet Avalanche (2WD/4WD)
- 2002 Chevrolet Avalanche (2WD/4WD)
- 2003 Chevrolet Avalanche (2WD/4WD)
- 2004 Chevrolet Avalanche (2WD/4WD)
- 2005 Chevrolet Avalanche (2WD/4WD)
- 2006 Chevrolet Avalanche (2WD/4WD)
FAQ
Will this kit work with my 6.0L truck?
It depends on your exhaust configuration. Most 6.0L applications use a 2-into-1 exhaust system, which this Y-pipe kit will not work with. Check your truck's exhaust configuration before ordering — if you have a single exhaust setup, this kit will work. If you have a 2-into-1 system, consider the Speed Engineering X-pipe kit instead, which can work with 2-into-1 systems but requires fabrication for connection.
Will this fit my 2500-series truck?
Earlier 2500-series trucks may have fitment issues. Earlier model years have the upper control arms mounted on top of the chassis (rather than below), which can cause header clearance problems. Verify your specific year and chassis configuration before ordering.
Will I get a check engine light after installing this kit?
Yes. The rear downstream O₂ sensors are not used with this system, which will trigger a catalyst efficiency code. This must be resolved through PCM tuning and cannot be cleared by simply resetting the ECU.
Do these headers have air or EGR fittings?
No. These are a race version and do not include air or EGR fittings. They are not compatible with emissions equipment.
Will these fit with a 4L80E transmission?
These headers may require trimming of the bellhousing ears on 4L80E transmissions for proper clearance.
What is included in this kit?
The kit includes a pair of 1-7/8" stainless longtube headers, a 3" off-road Y-pipe, two MLS exhaust gaskets, and zinc-coated header bolts. An upgrade to stainless ARP bolts is available at checkout. Speed Engineering LS spark plug wires and plug wire fire sleeves can also be added at the time of purchase.
How much horsepower does this kit add?
Speed Engineering's 1-7/8" longtube headers are dyno proven to add over 25 rear-wheel horsepower on 1999–2006 GMT800 applications compared to stock exhaust manifolds.
What material are these headers made from?
304 natural stainless steel with full TIG-welded construction, CNC-machined flanges, and merge spikes.
Are these headers street legal?
No. These are race-only headers intended for closed-course competition use only. Installation on a street-driven vehicle may violate the Clean Air Act (42 U.S.C. 7522(a)(3)).
⚠️ Race Use Only: This product is manufactured and sold for installation on vehicles used solely for competition. Once installed, the vehicle may not be used, registered, or licensed for use on a public road or highway. Installation on a street-driven vehicle may violate the Clean Air Act 203(a)(3), 42 U.S.C. 7522(a)(3).
