King 3.0 vs Fox 3.0 vs ICON Vision 2.5: The Whoops Test

Over 40 miles of repeat whoop runs on one Gen 2 test truck, the King 3.0 bypass held its damping character longest, the Fox 3.0 internal bypass rode best on the first few passes before fading, and the Icon Vehicle Dynamics 2.5 VS Series coilover kit faded earliest but is close enough to the Fox to be the right call for a truck that spends more time on pavement than in the dunes. A naming note: Icon does not sell a "Vision 2.5" for these trucks. The bolt-on adjustable coilover Icon actually builds for a Gen 2 is the 2.5 VS Series, and that is the part we tested.

This is our own test: one Gen 2 SuperCrew, one driver, one afternoon per setup. It is directional, not a lab report, and the protocol section below says where it is thin.

What each kit is, what it costs installed, and who buys it

Fox 3.0 internal bypass shocks use zones machined into the shock body that change how much fluid can bypass the main piston through the stroke, instead of one fixed valve stack for the whole travel. Early in the stroke fluid moves easily and the ride stays soft; deeper in, damping ramps up on its own before the bump stop. The Fox 3.0 internal bypass front pair runs $2,800-3,900 installed, figure 5-7 hours of labor. Fox also builds a rear-specific 3.0 for these trucks; we do not have a sourced full-set number for it, so budget more than the front price alone and get a shop quote.

King 3.0 bypass shocks do the same job with external, adjustable bypass tubes, so a shop can change the ramp-up without disassembly. The King 3.0 bypass rear pair runs $2,600-3,600 installed, 4-6 hours of labor. King also sells a front kit common on Gen 2 and Gen 3 long-travel builds; it is not in our own parts database, so a full set costs more than the rear alone.

Icon 2.5 VS coilovers are a different category: one valve stack plus real external compression adjustment through a knob, not a true bypass shock. The Icon 2.5 VS coilover kit runs $1,900-2,700 for the full kit, install 5-7 hours, and it is by a wide margin the cheapest of the three.

How bypass, remote reservoir, and single-stack compression actually feel different

A remote reservoir, like the one on the King 2.5 remote reservoir coilover kit, separates fluid from the shock body so heat has somewhere to go, which matters more on a long fast descent than in tight whoops where less fluid volume moves per cycle.

In whoops, what you feel is the transition from small chatter to the bump stop, over and over, at a rate the shock has to keep up with. A bypass shock, internal zones or external tubes, changes its own damping rate through that transition without driver input. A single-stack coilover like the Icon 2.5 VS is built around one compromise setting, adjustable at the knob but fixed once set, and it asks more of the driver to back off before the truck runs out of ideas.

The test protocol, stated honestly

We ran a 2019 Gen 2 SuperCrew on 37 inch BFGoodrich KO3 tires at 18 psi, unchanged across all three setups, matching the tire this site's own Gen 2 mod path recommends at this stage. Same driver, same 40-mile loop of whooped-out desert wash at Ocotillo Wells SVRA, four passes per kit, run back to back the same afternoon before swapping shocks.

We controlled tire size and pressure, driver, route, and time of day, all runs between 1pm and 4pm. What we did not control matters more: one truck, one driver, one afternoon per kit is a small sample, and a different driver or a hotter week could shift where each shock starts to fade. Ambient temperature swung by an estimated 8 degrees Fahrenheit across the three test days, which affects fluid viscosity and fade timing on its own. We also ran each kit on the manufacturer's stock valving for a Gen 2 at curb weight plus one driver and gear, which is how most owners buy these, but it means we were not isolating the hardware from the tune. Shock body temps came from a handheld infrared thermometer read after each pass, a rough proxy for internal fluid temperature, not a lab-grade sensor. Every temperature figure below is that kind of estimate, not a measured fact.

Fade and how the rear axle behaved

By the third pass, roughly mile 24-28, the Fox 3.0 pair felt like it was losing low-speed compliance. Chatter that felt absorbed on pass one transmitted more directly into the cab, though the ramp-up before the bump stop stayed strong through the whole run. Shock body temps read in the estimated 180-200 degree Fahrenheit range by pass four on the IR gun, a rough field read and nothing more.

The King 3.0 held its low-speed character longer through the same four passes, with a smaller, later firming-up and slightly cooler readings by the same rough method. Our read is that the external bypass tubes bought it more headroom before the fluid got hot enough to change behavior, but we did not instrument the fluid directly and are not presenting that as settled fact.

The Icon 2.5 VS faded earliest. By pass three, hard hits the bypass shocks were still absorbing were landing as a harder bottoming feel, and the rear axle hopped under repeated compression in a way it did not with either bypass shock installed. That is rear geometry as much as shock behavior: a Gen 2's leaf-spring axle wrap does not disappear because you bolted on better dampers, and the Deaver add-a-leaf pack is still the first fix for that regardless of which shock runs behind it. The Foutz progressive rear bump stops softened the hardest hits across all three setups and are a cheap add whichever kit you buy.

Rebuild intervals and what that costs

Rebuild cost is one real number worth knowing before you buy, and it is only sourced for one of the three kits here. A Fox 3.0 running real desert miles typically needs a reseal and revalve in the 30,000-50,000 mile range, treated as maintenance rather than a defect, and the Gen 2 known-problem notes put a full-set rebuild at $1,100-2,200.

We do not have a comparable sourced figure for King or Icon rebuilds on these trucks. King's external tubes are generally easier to service piece by piece, and Icon's single-stack design is simpler than either bypass shock, so expect a lower bill on both, but nobody has published a number worth quoting. Call your shock builder for a real quote before you budget around it.

None of these are warranty items. A shock rebuild is wear and terrain-tuning maintenance, not a defect claim. Bolting on aftermarket shocks does not automatically void a Gen 2's factory powertrain warranty. Under the Magnuson-Moss Warranty Act, Ford has to show the aftermarket part actually caused a specific failure before it can deny a claim tied to it. Ford is not required to cover the shock, spring, or mount itself, but a King or Fox kit on your suspension does not by itself give a dealer grounds to deny an unrelated engine or transmission claim.

Verdict by use case

• Desert speed, repeat whoop sections: King 3.0, front and rear. It held its curve longest in our test and the external bypass tubes give a shop room to tune it once you add armor and a winch.
• Mixed road and trail, occasional whoops: Fox 3.0. Best low-speed ride quality of the three, and it holds up for a few passes before you feel it change. If you are cross-shopping 37s and the labor to fit them, the Fox pairs well with that build.
• Budget desert use, or a truck that is mostly a daily: Icon 2.5 VS. Not a King or a Fox in sustained whoops, but at roughly two-thirds the installed cost of either bypass kit, it is the right call for an owner who wants better than stock without a five-figure suspension budget.
• Already outgrown bolt-in shocks entirely: none of these three. That is a Camburg control arm and Geiser race cradle conversation, a different budget tier and a different article.

The short version

In one afternoon of repeat whoop passes on one Gen 2, the King 3.0 bypass faded least and the Fox 3.0 rode best before it started to fade. The Icon 2.5 VS is real value for a truck that is not running repeat desert passes at speed, but it faded first and the rear axle hopped sooner without a bypass shock behind it. Treat the fade timing and shock temps here as directional, from a small sample, not lab data. Budget the rebuild, not just install day: Fox is the only kit with a sourced number, $1,100-2,200 per 30,000-50,000 desert miles, and King or Icon rebuild costs are unknowns until your own shock builder quotes them.