Cognito 1" SM Series Leveling Kit with Fox 2.5 Elite Shocks | 2019-2025 AT4/AT4X/Trail Boss/ZR2

The Obsidian Vision

The AT4, AT4X, Trail Boss, and ZR2 arrive from the factory with a meaningful head start — factory ride height already elevated, rear block already in, black trim and paint-matched bumpers already dialed — but the front suspension geometry is still compromised by a nose-down rake and shocks that leave significant damping performance on the table, regardless of whether the truck came with base shocks or Multimatic DSSV units. The Cognito 1-Inch SM Series Leveling Kit with Fox 2.5 Performance Elite Series Remote Reservoir Shocks resolves both problems simultaneously: the Cognito SM Series Upper Control Arm Kit corrects the ball joint angle, adds 1 inch of front droop travel, and converts that droop travel gain into 1 inch of additional front ride height — eliminating the rake and maintaining the minimum 3 inches of droop travel required for optimum ride quality. The Fox 2.5 Performance Elite Series shocks with remote reservoirs then deliver the damping precision and thermal management that the factory suspension — including the Multimatic DSSV — cannot match at this price point, completing a front suspension system that is engineered to perform rather than merely equipped to look the part. Made in the USA.

Concierge Fitment Guarantee

Every order is manually reviewed by our technicians to ensure 100% compatibility with your build before we ship.

Engineering Breakdown

• Corrects the front ball joint operating angle via the Cognito SM Series Upper Control Arm Kit, adding 1 inch of front droop travel and converting that gain into 1 inch of additional front ride height — eliminating the factory nose-down rake while maintaining the minimum 3-inch droop travel threshold required for consistent ride quality and long-term suspension component integrity.
• Eliminates the damping limitations of the factory front shocks — including the Multimatic DSSV units on AT4X and ZR2 — through the Fox 2.5 Performance Elite Series remote reservoir shocks, which use a remote reservoir to maintain consistent oil volume and temperature across the full suspension travel range, preventing the fade and harshness that develop in non-reservoir shocks under sustained use.
• Maximizes the suspension travel opportunity available on the AT4/AT4X/Trail Boss/ZR2 platform's factory-elevated ride height, using the Cognito UCA's corrected geometry to unlock the full droop travel range that the factory upper arm's compromised ball joint angle prevents these trucks from utilizing at their stock ride height.

The AT4 and Trail Boss platforms arrive with factory shocks that are adequate for light off-road use but are not valved or sized for the sustained damping demands of aggressive off-road driving or high-speed dirt road use at elevated ride heights. The AT4X and ZR2 Multimatic DSSV shocks are a meaningful improvement but remain a position-insensitive design without the reservoir volume required to prevent oil aeration and fade under sustained use. The Fox 2.5 Performance Elite Series remote reservoir shock addresses both limitations: the 2.5-inch shock body provides increased oil volume relative to the factory shock, and the remote reservoir maintains a constant oil supply to the piston, preventing cavitation and aeration that cause fade during sustained off-road or high-speed use. The Cognito SM Series upper control arm's boxed sheet-metal construction, corrected ball joint geometry, and polyurethane pivot bushings ensure the corrected geometry holds under the lateral and longitudinal loads generated by the elevated ride height and increased suspension travel this system unlocks. All components are manufactured in the USA. At 145 lbs, this kit ships via LTL freight carrier with residential delivery included.

Audit Table

Verified Fitment (OFAS Standard)

✅ CONFIRMED — AT4/AT4X/Trail Boss/ZR2 Models Only:
2019–2025 GMC Sierra 1500 AT4 4WD
2022–2025 GMC Sierra 1500 AT4X 4WD
2019–2025 Chevrolet Silverado 1500 LT Trail Boss 4WD
2019–2025 Chevrolet Silverado 1500 Custom Trail Boss 4WD
2022–2025 Chevrolet Silverado 1500 ZR2 4WD

❌ REQUIREMENTS:
⚠️ Standard Model Incompatibility: This kit is engineered specifically for AT4, AT4X, Trail Boss, and ZR2 models, which are factory 2 inches taller front and rear than standard Silverado/Sierra 1500 trims. Standard models (WT, Custom, LT, RST, LTZ, High Country, Denali) require the addition of a rear lift block and bump stop spacer to use this kit — without those components, the front-to-rear height ratio will be incorrect.
Requires front alignment immediately post-installation to reset caster and camber to specification.
Requires ADAS recalibration (adaptive cruise, forward collision alert, lane keep assist) after any ride height change.
Requires 4WD drivetrain — this kit is not designed for 2WD applications on the standard Silverado/Sierra 1500 platform.
Shipping Notice: At 145 lbs, this kit ships via LTL freight carrier. Residential delivery is included.

Installation & Technical Notes

Estimated Install Time: 4-Hour DIY Install (front system only, with basic lift equipment and hand tools)
Alignment Required: Yes — front caster and camber must be reset post-installation. Preferred caster: +3.5° to +4.5°; camber within ±0.5° of zero.
Torque Specifications: Refer to Cognito's included instruction sheet for all UCA and shock mount hardware torque values — torque all fasteners with the suspension at ride height.
ADAS Recalibration: AT4X and ZR2 models equipped with Super Cruise, adaptive cruise control, forward collision alert, or lane-keep assist require front camera and radar recalibration after installation.
Multimatic DSSV Note (AT4X/ZR2): The factory Multimatic DSSV rear shocks are retained — this kit replaces front shocks only. Rear shock replacement is a separate upgrade decision.
Shipping Notice: At 145 lbs, this kit ships via LTL freight carrier. Residential delivery is included. A delivery appointment will be scheduled by the carrier.

Wheel & Tire Fitment

Recommended Tire Size: Up to 35x12.50R18 at the 1-inch front lift increment on AT4/AT4X/Trail Boss/ZR2 factory-elevated ride height
Wheel Width: 8–9 inches recommended
Maximum Backspacing: 5.0 inches with 35-inch tires to prevent inner fender contact at full compression
Recommended Offset: 0mm to +18mm — negative offset wheels increase scrub radius and are not recommended with corrected-geometry upper arms

Our team is standing by to verify your specific trim (AT4, AT4X, Trail Boss, ZR2), ADAS configuration, and tire setup. Purchase with confidence; we review every build.