Building an LS swap into your 2WD GMT400 OBS C1500 and want a complete exhaust solution? This full kit pairs Speed Engineering's 1-7/8" LS swap longtube headers with a 3" off-road X-pipe, MLS exhaust gaskets, and zinc-coated header bolts — everything you need to replace the restrictive factory exhaust manifolds with a free-flowing stainless system designed for significant horsepower gains and an aggressive exhaust tone. Dyno proven and engineered specifically for great fitment on the OBS platform.
Built from 304 natural stainless steel with mandrel-bent primary tubes, CNC-machined flanges, and merge spikes throughout.
⚠️ Important Installation Notes:
- 2WD applications only — these headers will NOT fit 4WD C1500 trucks
- LS swap applications only — NOT compatible with SBC or BBC engines
- Rear downstream O₂ sensors are not used — a check engine light for catalyst efficiency will appear and must be disabled via PCM tuning
- Due to older vehicle frame clearance, headers fit very tight and require Speed Engineering spark plug wires
- Adjustable motor mounts with 1" offset back are required for proper fitment
- 4L80E or older Turbo 350/400 transmission — bellhousing ears may need to be trimmed for proper clearance
- Off-road X-pipe kit requires a modified or aftermarket crossmember for proper fitment. Compatible with Suspension Engineering transmission crossmember with required shims (4L60 will need 3 shims)
Kit Includes:
- 1 Pair of 1-7/8" Stainless Longtube Headers
- 1 Three-inch Off-Road X-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:
- 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
- Engineered for Great Fitment on the OBS Platform
- 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. 2WD applications only — will NOT fit 4WD trucks.
Chevrolet C1500 Truck (2WD) — GMT400 OBS
- 1988 Chevrolet C1500 Truck (2WD) — LS Swap
- 1989 Chevrolet C1500 Truck (2WD) — LS Swap
- 1990 Chevrolet C1500 Truck (2WD) — LS Swap
- 1991 Chevrolet C1500 Truck (2WD) — LS Swap
- 1992 Chevrolet C1500 Truck (2WD) — LS Swap
- 1993 Chevrolet C1500 Truck (2WD) — LS Swap
- 1994 Chevrolet C1500 Truck (2WD) — LS Swap
- 1995 Chevrolet C1500 Truck (2WD) — LS Swap
- 1996 Chevrolet C1500 Truck (2WD) — LS Swap
- 1997 Chevrolet C1500 Truck (2WD) — LS Swap
- 1998 Chevrolet C1500 Truck (2WD) — LS Swap
GMC C1500 Truck (2WD) — GMT400 OBS
- 1988 GMC C1500 Truck (2WD) — LS Swap
- 1989 GMC C1500 Truck (2WD) — LS Swap
- 1990 GMC C1500 Truck (2WD) — LS Swap
- 1991 GMC C1500 Truck (2WD) — LS Swap
- 1992 GMC C1500 Truck (2WD) — LS Swap
- 1993 GMC C1500 Truck (2WD) — LS Swap
- 1994 GMC C1500 Truck (2WD) — LS Swap
- 1995 GMC C1500 Truck (2WD) — LS Swap
- 1996 GMC C1500 Truck (2WD) — LS Swap
- 1997 GMC C1500 Truck (2WD) — LS Swap
- 1998 GMC C1500 Truck (2WD) — LS Swap
FAQ
What is included in this kit?
The kit includes a pair of 1-7/8" stainless longtube headers, a 3" off-road X-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.
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.
Will these headers fit my 4WD C1500?
No. These headers are designed for 2WD C1500 applications only and will not fit 4WD trucks. For 4WD K1500 applications see part 25-1011 (1-7/8") or 25-1077 (2").
Do I need special spark plug wires?
Yes. Due to tight frame clearance on older OBS truck platforms, Speed Engineering spark plug wires are required for proper fitment. They can be added to the kit at the time of purchase.
Do I need special motor mounts?
Yes. Adjustable motor mounts with a 1" offset back are required for proper fitment with these headers.
Does the off-road X-pipe bolt directly to the factory crossmember?
No. The off-road X-pipe requires a modified or aftermarket crossmember for proper fitment. The Suspension Engineering transmission crossmember is compatible with required shims — a 4L60 transmission will need 3 shims.
Will these fit with a 4L80E or older Turbo 350/400 transmission?
These headers may require trimming of the bellhousing ears on 4L80E or older Turbo 350/400 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 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).
