Building an LS swap into your GMT400 OBS K1500? Speed Engineering's 1-7/8" LS swap longtube headers are built specifically for the 1988–1998 K1500 4WD platform — mandrel bent, TIG-welded, and CNC-machined for a precise fit on the most popular classic GM truck LS conversion. Compatible with the full LS engine family from 4.8L through 6.2L including LS1, LS2, LS3, LS6, and LSA. Dyno proven to deliver over 25 rear-wheel horsepower over stock manifolds.
Built from 304 natural stainless steel with merge spikes and standard graphite manifold gaskets included. Race version — no air or EGR fittings.
⚠️ Important Installation Notes:
- 4WD applications only — these headers will NOT fit 2WD K1500 trucks
- Race version with no air or EGR fittings — not compatible with emissions equipment
- 4L80E transmission — bellhousing ears may need to be trimmed for proper clearance
- Y-pipe kit may require modifications for attaching to the factory exhaust
Features:
- 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
- Mandrel Bent Tubing — Consistent tube diameter through every bend; no crimping, no restriction
- CNC Machined Flanges — Precision fit at the cylinder head 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
- Race Version — No Air or EGR Fittings
- Standard Graphite Manifold Gaskets Included
- Dyno Proven — 25+ RWHP gain on LS 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. 4WD applications only — will NOT fit 2WD trucks.
Chevrolet K1500 Truck (4WD) — GMT400 OBS
- 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) — GMT400 OBS
- 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
FAQ
Will these headers fit my 2WD K1500?
No. These headers are designed for 4WD K1500 applications only and will not fit 2WD trucks.
What is the difference between the 1-3/4", 1-7/8", and 2" K1500 LS swap headers?
The primary tube diameter is the key difference. The 1-3/4" headers are a great choice for mild LS swap builds and work well across a broad RPM range on lower displacement engines. The 1-7/8" headers offer a step up in flow and are well suited for most street and performance LS swap builds across the full LS engine family. The 2" headers are best suited for higher RPM builds with more aggressive modifications and larger displacement engines where maximum flow is the priority.
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 my Y-pipe kit bolt directly to the factory exhaust?
The Y-pipe kit may require modifications for attaching to the factory exhaust on these applications.
Will these fit with a 4L80E transmission?
These headers may require trimming of the bellhousing ears on 4L80E transmissions for proper clearance.
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.
How much horsepower do these headers add?
Speed Engineering's 1-7/8" LS swap longtube headers are dyno proven to add over 25 rear-wheel horsepower compared to stock exhaust manifolds on LS applications.
What material are these headers made from?
304 natural stainless steel with full TIG-welded construction, CNC-machined flanges, and merge spikes.
Are gaskets included?
Yes. Standard graphite manifold gaskets are included with the headers.
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).
