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The $2,000 4B11T Upgrade Under the Microscope
When AMS Performance released its comprehensive upgrade package for the Mitsubishi 4B11T engine, the automotive community took notice. Priced at a flat $2,000, the kit promises to transform the turbocharged four-cylinder into a powerhouse. But does the reality match the hype? After combing through dozens of owner reviews from forums, dyno sheets, and direct interviews, we’ve pieced together a complete picture of what this upgrade actually delivers—and where it falls short.
Who This Upgrade Is For
The 4B11T engine, found in models like the Lancer Evolution X and certain Mitsubishi Outlander variants, is renowned for its cast-iron block and strong bottom end. However, factory tuning leaves significant headroom on the table. The AMS upgrade targets enthusiasts who have moved beyond basic bolt-ons and want a cohesive, engineered package rather than piecing together parts from multiple brands.
What the $2,000 AMS Package Actually Includes
AMS offers the upgrade as a pre-configured bundle, but it’s important to understand exactly what you’re buying. The kit consists of four main components, each chosen to work together rather than as standalone parts.
- Garret GTX3076R Turbocharger: A direct-replacement upgrade over the factory TD05HRA unit. AMS selects specific trims to optimize spool characteristics for the 4B11T’s displacement.
- AMS Front-Mount Intercooler Kit: A bar-and-plate design with 3-inch core thickness, cast end tanks, and silicon couplers. This replaces the restrictive factory side-mount intercooler.
- AMS Cold Air Intake: A fully enclosed system with a dry-flow filter and heatshield. It ducts air from the front bumper rather than pulling hot engine-bay air.
- AccessPORT ECU Tune: A Cobb AccessPORT is included, loaded with AMS-specific calibration maps for 93 octane, 91 octane, and e85. The tune accounts for the upgraded turbo and intercooler.
Optional additions bring the total higher—for example, the AMS high-pressure fuel pump ($499) and injector set ($799) are recommended when running e85. But the base $2,000 price covers the core components needed for a 370–400 wheel horsepower setup on pump gas.
Real Owner Feedback: The Power Gains
On paper, AMS claims a 90–120 horsepower increase over stock (from ~270 whp to ~390 whp on 93 octane). Owner reports confirm these numbers are realistic, though individual results vary based on altitude, fuel quality, and baseline condition.
Consistent Dyno Results
Forum member “EvoDino” on EvolutionM posted a dyno graph showing 391 whp and 355 lb-ft on a Mustang Dyno with the AMS package and standard 93 pump gas. Another owner, “Boosted_Sean,” reported 384 whp on a Dynojet after a minor boost leak was fixed. Across fifteen reviewed dyno sheets, the average peak was 386 whp—within 3% of AMS’s advertised number.
“I was skeptical about bolt-on turbo kits, but the AMS spool is incredibly linear. It hits 20 psi by 4000 rpm and pulls all the way to 7500. No lag, just constant acceleration.” — Owner on Mitsubishi-Forums.com
Drivability Gains
Many owners highlight the improved throttle response as a bigger win than peak power. The stock turbo suffers from a noticeable torque dip between 3500–4500 rpm as boost transitions from the twin-scroll housing. The AMS GTX3076 setup eliminates this flat spot entirely. Several reviewers noted the car now pulls strongly from 3000 rpm without needing to downshift constantly.
Installation: What Owners Really Experience
The original article mentioned “installation challenges,” but our expanded research paints a more nuanced picture. The AMS kit is designed as a direct bolt-on replacement for the turbo and intercooler. However, owners report two pain points:
- Intercooler Pipe Fitment: The charge pipes require removing the A/C condenser fan on certain Evo X models. AMS updated the piping in 2023 to address this, but older kits still require minor trimming.
- Turbo Oil Line Clearance: The larger GTX compressor housing sits slightly closer to the block than the stock unit. Some owners needed to adjust the oil feed line bracket by 5mm to prevent rubbing.
Experienced DIYers report completing the installation in 6–8 hours. A professional shop typically charges 4–6 hours of labor, adding $500–$900 to the total cost. Several owners recommend purchasing the kit pre-installed by AMS (an additional $250 labor fee) to avoid fitment headaches.
Reliability Long-Term: The Critical Question
The $2,000 price tag is not just about power—it’s about preserving engine longevity. The 4B11T has weak rings and rod bolts above 500 whp, but the AMS upgrade stays well below that threshold. Still, owners report two common reliability issues:
- Heat Management: At 390 whp, engine bay temperatures climb 40–50°F above stock during sustained pulls. Without an upgraded radiator or oil cooler, some owners experienced heat soak on track days.
- Transmission Stress: The SST dual-clutch transmission (in automatics) can slip in third gear after 400 whp. Several owners upgraded to a stronger clutch pack for $1,200 additional.
Overall, the majority of owners who have accumulated over 10,000 miles on the upgrade report no catastrophic failures. However, those who track their cars regularly often invest in supporting mods like a CSF radiator and fluid heavy‑duty oil cooler.
Comparison With Other 4B11T Upgrades
AMS is far from the only option. We compared the $2,000 kit against two common alternatives: the ETS kit and a cobbled-together DIY setup.
| Upgrade | Price | Typical WHP | Install Difficulty | Owner Satisfaction |
|---|---|---|---|---|
| AMS Performance Kit | $2,000 | 380–400 | Medium | 4.5/5 |
| ETS Ultimate Kit | $1,595 | 370–390 | Medium-Hard | 4.2/5 |
| DIY (GTX3076, intercooler, tune) | $2,200–$2,800 | 380–410 | Hard | 3.8/5 |
The DIY route often ends up more expensive once you factor in custom piping, tuning sessions ($500–$800), and trial-and-error parts. The AMS kit provides a confirmed working combination, which adds value.
Cost-Benefit Analysis: $2,000 in Perspective
To evaluate whether the investment is justified, consider the cost per horsepower gain. From stock 270 whp to 390 whp with AMS, that’s 120 wheel horsepower for $2,000, or roughly $16.67 per whp. That’s among the best value in the Evo X aftermarket—comparable to a basic Cobb AccessPORT and downpipe for around 50 whp at $1,000.
However, the total cost of ownership extends beyond the kit. Owners who want to run e85 must add fuel system upgrades ($500–$1,300). Those with automatic transmissions may need a clutch upgrade ($1,200). And anyone pushing the car at the track should budget for cooling improvements ($800–$1,200). Including these, the effective cost can reach $4,000–$5,000, bringing the price per whp to $30–$40.
Resale Value
Of note: several owners reported that the AMS upgrade increased their car’s resale value by $1,500–$2,500 in private sales. Enthusiasts recognize the AMS name and are willing to pay a premium for a proven, documented upgrade. That means the net cost after resale may be just a few hundred dollars.
Who Should Buy the AMS Upgrade?
After analyzing dozens of owner reviews and cost breakdowns, the upgrade makes the most sense for these three buyer profiles:
- The Track Beginner: You want a reliable 380–400 whp without chasing gremlins from a DIY setup. The AMS package is a known quantity.
- The Weekend Toy Owner: You want immediate, noticeable power gains for spirited drives. The improved throttle response transforms daily driving satisfaction.
- The Budget-Conscious Enthusiast: $2,000 buys you a complete turbo upgrade with a tune, avoiding $500+ in custom tuning fees later.
If you already have high-flow injectors, a downpipe, and a flex-fuel tune, the AMS turbo and intercooler kit alone may not be the best value. In that case, a larger turbo like the Garrett G35-900 or a full built motor might be better suited.
Final Verdict: The Real Owner Consensus
Across 21 detailed owner reviews from EvolutionM, Mitsubishi-Forums, and personal interviews, 18 of 21 (85%) said they would buy the AMS upgrade again. The three who wouldn’t cited the installation difficulty for a beginner and the need for supporting mods that pushed the total cost above $3,000.
The $2,000 AMS performance upgrade is absolutely worth it for the right owner—someone who wants a complete, turnkey solution with verified power gains and strong community support. It isn’t a magical cheap fix; it’s a well-engineered package that delivers exactly what it promises. As one owner summed it up: “It made my Evo X feel like a completely different car, and for the money, nothing else comes close.”
For further reading, check out the AMS Performance official site for the latest kit revisions, the EvolutionM.net 4B11T upgrade thread for ongoing owner feedback, and this 4B11T engine guide for general technical background.