Dropping an LS into your OBS K1500 4x4? This complete bolt-on system pairs Speed Engineering's 1-3/4" LS swap longtube headers with a 3" off-road Y-pipe — replacing the 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. 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:
- 4WD K1500 only — will NOT fit 2WD applications. This kit only works on 4 wheel drive 1/2 ton chassis
- The Y-pipe kit might require modifications for attaching to the factory exhaust
- 4L80E transmission: Bellhousing ears may need to be trimmed for proper clearance
Kit Includes:
- 1 Pair of 1-3/4" 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 1-3/4" 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
- 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 LS swap applications
- Compatible with 4.8L, 5.3L, 6.0L, 6.2L, LS1, LS2, LS3, LS6, and LSA Engines
- LS V8 Engines Only
Vehicle Applications:
Note: All applications listed are LS swap conversions. The OBS K1500 never came with a factory LS engine. These headers are for 4WD applications only.
Chevrolet K1500 Truck (4WD) — LS Swap
- 1988 Chevrolet K1500 Truck (4WD) — LS Swap
- 1989 Chevrolet K1500 Truck (4WD) — LS Swap
- 1990 Chevrolet K1500 Truck (4WD) — LS Swap
- 1991 Chevrolet K1500 Truck (4WD) — LS Swap
- 1992 Chevrolet K1500 Truck (4WD) — LS Swap
- 1993 Chevrolet K1500 Truck (4WD) — LS Swap
- 1994 Chevrolet K1500 Truck (4WD) — LS Swap
- 1995 Chevrolet K1500 Truck (4WD) — LS Swap
- 1996 Chevrolet K1500 Truck (4WD) — LS Swap
- 1997 Chevrolet K1500 Truck (4WD) — LS Swap
- 1998 Chevrolet K1500 Truck (4WD) — LS Swap
GMC K1500 Truck (4WD) — LS Swap
- 1988 GMC K1500 Truck (4WD) — LS Swap
- 1989 GMC K1500 Truck (4WD) — LS Swap
- 1990 GMC K1500 Truck (4WD) — LS Swap
- 1991 GMC K1500 Truck (4WD) — LS Swap
- 1992 GMC K1500 Truck (4WD) — LS Swap
- 1993 GMC K1500 Truck (4WD) — LS Swap
- 1994 GMC K1500 Truck (4WD) — LS Swap
- 1995 GMC K1500 Truck (4WD) — LS Swap
- 1996 GMC K1500 Truck (4WD) — LS Swap
- 1997 GMC K1500 Truck (4WD) — LS Swap
- 1998 GMC K1500 Truck (4WD) — LS Swap
Frequently Asked Questions:
Q: Will this kit fit a 2WD C1500?
No. This kit only fits 4WD K1500 trucks. It will NOT fit 2WD applications.
Q: Does this kit work on a 3/4 ton or 1 ton truck?
No. This kit only works on 4 wheel drive 1/2 ton chassis.
Q: What is the difference between this kit and the 1-7/8" version (25-1011)?
The primary tube diameter is the key difference. The 1-3/4" headers are a strong choice for most LS swap builds across a broad RPM range. The 1-7/8" headers offer a step up in flow for more aggressive builds with supporting modifications. Both cover the same 1988–1998 K1500 4WD platform.
Q: Does the Y-pipe bolt right up to the factory exhaust?
It might require modifications. The Y-pipe kit may need adjustments for proper attachment to the factory exhaust system on this older chassis.
Q: Will these fit with a 4L80E transmission?
These headers may require trimming of the bellhousing ears on 4L80E transmissions for proper clearance.
Q: What is included in this kit?
The kit includes a pair of 1-3/4" 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.
Q: How much horsepower does this kit add?
Speed Engineering's 1-3/4" longtube headers are dyno proven to add over 25 rear-wheel horsepower on LS swap K1500 applications compared to stock.
Q: What LS engines are these headers compatible with?
These headers are compatible with GM LS V8 engines including 4.8L, 5.3L, 6.0L, 6.2L, LS1, LS2, LS3, LS6, and LSA.
Q: What material are these headers made from?
304 natural stainless steel with full TIG-welded construction, CNC-machined flanges, and merge spikes.
Q: 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).