KA24E Headers for 1990–1995 Nissan Hardbody D21 4WD
Replace an aging cast exhaust manifold with a stainless steel header designed to give the exhaust path a smoother transition from the cylinder head. This Flashark header is listed for 1990–1995 Nissan Hardbody D21 pickups equipped with the 2.4L KA24E inline-four engine and 4WD drivetrain.
The 1.50-inch primary tubes lead into a 2.50-inch outlet, while the thick head and outlet flanges provide solid mounting surfaces. Silver and black finishes are available under separate SKUs.
Nissan Hardbody D21 Fitment
| Make | Model | Years | Engine | Drivetrain |
|---|---|---|---|---|
| Nissan | Hardbody D21 Pickup | 1990–1995 | 2.4L KA24E inline-four | 4WD / 4x4 only |
- Not intended for 2WD Nissan Hardbody models.
- Do not use this fitment for a KA24DE engine or a different Nissan platform.
- Existing exhaust modifications can change flange alignment and available clearance.
- Inspect the front driveshaft, steering components and surrounding underbody clearance before final tightening.
Technician’s note: Underbody clearance can vary with engine-mount condition, suspension height, previous repairs and the downstream exhaust position. Complete a full clearance check with the truck safely supported before operating the 4WD system.
Specifications
| Brand | FLASHARK |
|---|---|
| Part type | Exhaust header |
| Material | Stainless steel |
| Available finishes | Silver or black |
| Primary tube diameter | 1.50 inches |
| Outlet diameter | 2.50 inches |
| Cylinder-head flange thickness | 7/16 inch |
| Outlet flange thickness | 3/8 inch |
| Silver SKU | FLES08217 |
| Black SKU | FLES08358 |
| Product model references | EH28949X / ES08217 and EH28950X / ES08358 |
Key Features
- Designed around the 2.4L KA24E exhaust-port layout used in the listed Nissan Hardbody D21 4WD applications.
- Individual 1.50-inch primary tubes provide a smoother exhaust path than the compact cast-manifold layout.
- 2.50-inch collector outlet for connection to the remaining exhaust system.
- Stainless steel construction with silver and black finish options.
- 7/16-inch head flange and 3/8-inch outlet flange provide substantial mounting surfaces.
- Useful as a replacement or upgrade when the original cast manifold is cracked, leaking or heavily corroded.
Built for Better Exhaust Flow and a More Defined Tone
A tubular header gives each cylinder a more direct path into the collector. On a naturally aspirated KA24E, that layout can reduce restriction and support sharper throttle response and smoother exhaust movement, especially when the remaining exhaust system is in good condition.
The final sound depends on the catalytic converter, pipe diameter, resonator, muffler and exhaust-leak condition. A header can make the engine sound deeper and more mechanical, but it does not determine the complete exhaust tone by itself.
Stock Manifold vs. Tubular Header
| Area | Factory-Style Cast Manifold | Flashark Tubular Header |
|---|---|---|
| Construction | Compact cast design | Stainless steel primary tubes |
| Exhaust path | Short shared passages | Individual tubes merging at the collector |
| Outlet | Vehicle-specific factory connection | 2.50-inch outlet |
| Sound | Factory exhaust character | Can add a deeper, more defined mechanical tone |
| Installation check | Original equipment layout | Requires flange, sensor, steering and front-driveshaft clearance checks |
Header vs. Complete Nissan Hardbody Exhaust System
This product is an exhaust header, not a complete Nissan Hardbody exhaust system. It replaces the engine-side manifold section and connects the cylinder head to the downstream exhaust path.
A complete Nissan D21 exhaust can also include connecting pipes, a catalytic converter, resonator, muffler and tailpipe. The condition and design of those parts will affect sound, exhaust flow, installation and emissions performance.
For other exhaust components, visit the Flashark Exhaust Header collection.
Package and Installation Planning
Package contents vary by selected SKU. Select the required finish and SKU before ordering, and contact customer support if you need help identifying the correct configuration.
- Allow the engine and exhaust system to cool completely before removal.
- Inspect the cylinder-head sealing surface and downstream flange before installing the header.
- Replace damaged sealing components rather than reusing parts with visible crushing, cracking or heat damage.
- Start all fasteners before final tightening so the header and downstream exhaust can settle into alignment.
- Check the O2 sensor wiring path and keep the harness away from hot tubes and moving parts.
- Inspect clearance around the front driveshaft, steering system, transmission and underbody before starting the engine.
- Recheck fasteners and inspect for exhaust leaks after the first complete heat cycle.
Who This Header Is Best For
- Owners of a listed 1990–1995 Nissan Hardbody D21 4WD with a 2.4L KA24E engine.
- Trucks with a cracked, leaking or heavily corroded factory exhaust manifold.
- Owners looking for a stainless tubular header and a more defined exhaust tone.
- Buyers prepared to inspect drivetrain and exhaust clearance during installation.
- Vehicles whose downstream exhaust components are in serviceable condition or are being upgraded as part of the same project.
Who Should Choose a Different Part
- Owners of a 2WD Nissan Hardbody.
- Vehicles equipped with a KA24DE, Z24, V6 or another engine not listed in the fitment table.
- Buyers looking for a complete cat-back exhaust, muffler or full Nissan D21 exhaust system.
- Owners who cannot inspect front-driveshaft and steering clearance during installation.
- Vehicles that require a certified emissions replacement without supporting product-specific approval.
- Drivers who want to retain completely stock exhaust sound and construction.
Emissions and Street-Use Notice
Do not remove, bypass or disable the catalytic converter, O2 sensor or other emissions equipment when installing this header. Exhaust and emissions requirements vary by location. Check the rules that apply to your vehicle before installation or road use.
Shipping & Returns
Free U.S. Shipping: Orders are typically processed within 1–2 business days and delivered within 7–9 business days. Additional charges may apply to remote areas.
30-Day Returns: Unopened and unused items in their original packaging may be returned within 30 days of receipt. Return shipping is covered for verified quality issues.
Worry-Free Delivery: Optional protection against eligible loss, theft, delay, or transit damage is available at checkout.
Fitment & Compatibility
- Exclusively fits 1990-1995 Nissan Hardbody (D21) models factory-equipped with 2.4L KA24E Inline-4 engines and 4WD (4x4) ONLY
- ❌ ABSOLUTELY NO COMPATIBILITY WITH 2WD (2-wheel drive) models (NO EXCEPTIONS)
✅ Verified Fitment
| Brand | Model | Year Range | Full Compatible Specs |
|---|---|---|---|
| Nissan | Hardbody (D21) | 1990-1995 | 2.4L KA24E Inline-4 Engine; 4WD (4x4) Only |
- Not intended for 2WD Nissan Hardbody models.
- Do not use this fitment for a KA24DE engine or a different Nissan platform.
- Existing exhaust modifications can change flange alignment and available clearance.
- Inspect the front driveshaft, steering components and surrounding underbody clearance before final tightening.
Nissan Hardbody D21 KA24E Header FAQs
Q1: Which Nissan Hardbody trucks are listed for this header?
A1: It is listed for 1990–1995 Nissan Hardbody D21 pickups equipped with the 2.4L KA24E inline-four engine and 4WD drivetrain.
Q2: Will it fit a 2WD Nissan Hardbody?
A2: No. This configuration is intended for 4WD applications and should not be ordered for a 2WD truck.
Q3: Will it fit a KA24DE engine?
A3: No. The listed application uses the single-cam KA24E engine. Do not substitute KA24DE fitment based only on the shared 2.4L displacement.
Q4: Why should front-driveshaft clearance be checked?
A4: The header passes through a tight area near drivetrain and chassis components on a 4WD truck. Engine-mount condition, suspension height, previous repairs and exhaust alignment can affect the available clearance.
Q5: Is this a complete Nissan D21 exhaust system?
A5: No. It is the header section at the engine. Connecting pipes, catalytic converter, resonator, muffler and tailpipe are separate parts of the complete exhaust system.
Q6: Will it connect to the stock exhaust?
A6: The header has a 2.50-inch outlet. Inspect the downstream flange, pipe position and existing exhaust modifications before installation. Exhaust work may be required when the remaining system does not match the header outlet or alignment.
Q7: How much horsepower and torque will it add?
A7: Results depend on engine condition, the complete exhaust setup, ECU calibration and installation quality. A header alone should not be treated as a guaranteed horsepower or torque increase.
Q8: Does a KA24E need a tune after installing a header?
A8: Tuning needs depend on the complete vehicle setup and ECU behavior. Diagnose fuel control, ignition condition and sensor operation instead of assuming a header automatically requires or replaces calibration work.
Q9: Can this header cause a check-engine light?
A9: Exhaust leaks, damaged sensor wiring or an O2 sensor problem can contribute to a warning light. Keep the sensor wiring away from heat and moving parts, then diagnose any stored fault code before replacing additional components.
Q10: Will the exhaust become louder?
A10: A tubular header can make the engine sound deeper and more mechanical. Overall volume, rasp and highway drone depend mainly on the catalytic converter, pipe diameter, resonator, muffler and exhaust-leak condition.
Q11: Does the header remove the catalytic converter?
A11: Do not remove or bypass the catalytic converter or other emissions equipment during installation. Inspect the complete exhaust layout and retain the emissions components required for the vehicle and location.
Q12: What is included with the selected SKU?
A12: Package contents vary by selected SKU. Choose the required finish and SKU before ordering, and contact customer support if you need a detailed contents check.
Q13: Can this be installed at home?
A13: Installation requires safe vehicle support, removal of heat-cycled fasteners, flange alignment and checks around the steering and front driveshaft. Professional installation is recommended when the original hardware is heavily corroded or exhaust fabrication may be needed.
Q14: Who should not buy this header?
A14: Do not order it for a 2WD truck, an engine other than the listed KA24E, or a vehicle that requires product-specific emissions approval. It is also unsuitable for buyers looking for a complete cat-back exhaust or a guaranteed modification-free installation.