The Mitsubishi Lancer Evolution X is a modern interpretation of rally‑bred performance. Its 4B11T engine, all‑wheel drive, and sophisticated electronics made it an instant classic. For many owners, the sweet spot for a daily‑driver build is 400 wheel horsepower. At this level the car remains responsive, the engine lives a long life, and the chassis still feels balanced. Achieving 400 reliable horsepower requires more than bolting on a larger turbo. The stock internals have limits, and the fuel system runs out of headroom. A thoughtful combination of forged internal components, a carefully chosen turbo upgrade, and supporting modifications is the proven path. This guide breaks down the costs of each major category so you can budget realistically and avoid surprises.

The Foundation: Forged Internals

The 4B11T uses cast aluminum pistons and powdered‑metal connecting rods from the factory. These parts handle around 350–400 wheel horsepower on a good tune, but they become a liability beyond that. For a 400‑hp target, forged pistons and rods are the right investment. They not only handle the higher cylinder pressures but also reduce the risk of catastrophic failure should a tuning error occur.

Pistons

Forged pistons are available from multiple reputable manufacturers. Choices include Manley, CP‑Carillo, Wiseco, and the in‑house offerings from tuner shops. Prices vary with material (2618 vs. 4032 alloy), coating options, and whether rings and wrist pins are included.

  • Cost range: $600 – $1,200
  • Typical brands: Manley Platinum Series, CP‑Carillo, Wiseco Pro‑Tru
  • Additional items: Performance rings ($150–$250), upgraded wrist pins ($100–$200)

Connecting Rods

Forged rods are necessary to withstand the increased tensile and compressive loads. Manley H‑tuff and Oliver billet rods are popular choices, offering strength and weight parity with stock components. Many builders select rods with upgraded ARP 2000 or L19 fasteners.

  • Cost range: $500 – $1,100
  • Common options: Manley H‑tuff, Carrillo billet, K1 Technologies

Bottom‑End Labor and Machining

Forged internals require proper assembly. The block should be honed to the correct cross‑hatch for the new rings, and the crank must be checked for clearances. Many shops also recommend a balance job on the rotating assembly. Labor costs vary significantly by region and shop reputation.

  • Block prep (honing, decking): $300 – $600
  • Assembly labor: $800 – $2,000
  • Balance job: $200 – $400

Total estimated for forged internals (parts and labor): $2,400 – $4,800

The Heart: Turbocharger Upgrade

The stock Evo X turbo (a twin‑scroll IHI unit) can be pushed to around 350–370 whp with aggressive tuning and high boost. To reach 400 whp reliably, a larger compressor wheel or a completely different turbo housing is needed. The path you choose will affect the entire power curve and the cost significantly.

Stock‑Frame Upgrades

Many tuners offer upgraded compressor wheels that fit inside the stock housing (e.g., MAP EF2 or FP Green). These maintain factory spool characteristics while adding 20–40 whp. They are a budget‑friendly way to get close to 400 whp, but they often require a larger downpipe and a re‑tune.

  • Turbo cartridge / wheel upgrade: $700 – $1,500
  • Larger downpipe and ported manifold: $400 – $800

Full Aftermarket Turbocharger

For true 400‑hp capability with headroom, a larger turbo like the Precision 6062, Garrett GTX3071R Gen II, or a Forced Performance BBK is the better choice. These turbos require new oil/coolant lines, a different downpipe, and often a new intake pipe. They also increase lag, though modern billet wheels help.

  • Turbocharger, lines, and gaskets: $1,800 – $3,500
  • Turbo manifold (if not stock‐frame): $500 – $1,200
  • Downpipe and dump tube: $300 – $800
  • Installation labor: $500 – $1,500 (may increase if removing engine)

Boost Control and Wastegate

A quality electronic boost controller is strongly recommended to dial in transient response. External wastegates are only needed for non‑OEM manifold setups.

  • Electronic boost controller (e.g., Cobb, Grimmspeed): $250 – $500
  • External wastegate (if required): $300 – $600

Total estimated for turbo upgrade: $2,500 – $6,000

Fuel System Upgrades

The stock fuel pump and injectors run out of duty cycle at around 350–370 whp on gasoline. To reach 400 whp safely, you need increased fuel flow and the ability to command it. Running E85 is a popular choice because it provides knock resistance and allows more power, but it requires even larger injectors and pump capacity.

Fuel Injectors

High‑impedance injectors in the 1300–1700 cc range are common for 400 hp on gasoline, while 2000+ cc injectors are typical for E85.

  • Injectors (set of 4): $450 – $900
  • Popular brands: FIC, Injector Dynamics, Bosch (via OEM conversion)

In‑Tank Fuel Pump

A drop‑in 450‑lph pump (e.g., Walbro 450, AEM 340) supports 400 hp on pump gas. For E85, a dual pump setup or a larger single pump like a Walbro 525 may be needed.

  • Single in‑tank pump: $120 – $250
  • Dual pump hanger and wiring: $400 – $700

Fuel Pressure Regulation and Lines

The stock returnless system is adequate up to a point, but many builders switch to a return‑style system for better pressure stability at high flow. A fuel pressure regulator and new lines add cost.

  • Fuel pressure regulator (e.g., Aeromotive, Fuelab): $150 – $350
  • Lines, fittings, and rail (if needed): $200 – $500

Labor for Fuel System

  • Installation and wiring: $200 – $500

Total estimated for fuel system: $800 – $2,500

Tuning for 400 Horsepower

A custom tune is non‑negotiable. The factory ECU can be reprogrammed through platforms like Cobb Accessport (very popular for the Evo X) or EcuTek. Both allow full control of ignition timing, fuel maps, boost targets, and safety limits. The tuning session itself should be performed on a dynamometer by a reputable tuner with Evo X experience.

  • Tuning handheld or cable (Accessport or Tactrix): $500 – $700
  • Dyno tuning session (4–8 hours): $400 – $1,000 (depending on rates and complexity)
  • Ethanol sensor / flex‑fuel kit (if using E85): $300 – $600

Total estimated for tuning: $700 – $1,700

Supporting Modifications

Several other components must be upgraded to let the engine breathe, cool, and handle the additional power. Some of these are already accounted for in the turbo or fuel categories, but the following are common additions.

Exhaust System

A free‑flowing turbo‑back exhaust reduces backpressure and spool time. Most 400‑hp Evo X builds run a 3‑inch downpipe and cat‑back.

  • Downpipe (with catalytic converter if emissions are a concern): $250 – $600
  • Cat‑back exhaust: $400 – $1,200

Intercooler and Intake

The stock intercooler can be heat‑soaked on repeated pulls. A larger front‑mount or a high‑efficiency bar‑and‑plate core helps keep intake air temperatures in check. A cold‑air intake reduces restriction.

  • Upgraded front‑mount intercooler: $400 – $900
  • Short‑ram / cold‑air intake: $150 – $400

Cooling System

High‑power driving can stress the cooling system. An upgraded radiator, high‑flow thermostat, and possibly a larger oil cooler are prudent.

  • Aluminum radiator: $200 – $500
  • Oil cooler kit: $200 – $500

Drivetrain and Clutch

The stock clutch in the Evo X is marginal for 400 whp. A stronger twin‑ or triple‑plate clutch is recommended. If you have the SST (dual‑clutch), careful tuning of the transmission control unit and upgraded clutches may be needed—this adds significant cost.

  • Clutch for manual transmission: $600 – $1,500
  • SST upgrade (clutch pack + tuning): $1,500 – $3,500

Total estimated for supporting mods: $1,500 – $4,200 (manuals), $2,500 – $6,000 (SST)

Total Cost Breakdown Table

The following table aggregates the expected cost ranges for a 400‑whp Evo X build using a manual transmission. Prices assume professional labor for engine assembly and turbo installation. DIY labor will reduce costs but requires specialized tools and knowledge.

  • Forged internals (bottom end): $2,400 – $4,800
  • Turbo upgrade (full aftermarket): $2,500 – $6,000
  • Fuel system (pump gas): $800 – $2,500
  • Tuning (including handheld): $700 – $1,700
  • Supporting mods (exhaust, intercooler, intake, clutch): $1,500 – $4,200
  • Miscellaneous (gaskets, fluids, fasteners, incidentals): $200 – $600

Total estimated cost: $8,100 – $19,800

Real‑World Considerations

Labor Costs Vary Widely

Rates for a competent performance shop can range from $100 to $200 per hour. A complete build can take 40–80 hours of labor, not including the tuning session. If you live in an area with fewer shops, you may have to travel or pay a premium.

DIY vs. Turnkey

Doing the work yourself—especially engine removal, assembly, and turbo installation—can save thousands. However, mistakes can be costly. Most first‑time builders benefit from having a professional assemble the short block. The rest (turbo, fuel system, exhaust) can often be tackled by an experienced hobbyist with a lift and proper tools.

Reliability Trade‑Offs

400 whp is well within the capability of a properly built 4B11T. The key is the quality of the tune and the maintenance afterward. Frequent oil changes, quality spark plugs, and a conservative tune (avoiding knock) will keep the engine healthy. Many owners enjoy 40,000–60,000 trouble‑free miles on a build like this.

Hidden Costs

New OEM gasket sets, head studs, timing chain components, and water pump are advisable while the engine is apart. Adding these during the assembly adds maybe $300–$600 but prevents future headaches. Also, if your car has high mileage, consider upgrading the valvetrain (springs, retainers) if the budget allows—though not strictly required for 400 hp.

Conclusion

Building a 400‑horsepower Evo X with forged internals and an upgraded turbo is a rewarding project that delivers a thrilling driving experience without sacrificing daily usability. The costs are substantial, ranging from roughly $8,000 to $20,000 depending on parts choices and labor, but the result is a car that is both quick and robust. By understanding where the money goes—internals, turbo, fuel, tuning, and supporting mods—you can plan your build step by step, prioritize quality components, and avoid the pitfalls of cutting corners. For further reading and community advice, visit EvolutionM.net (community forums) or consult with established tuners like MAPerformance and EcuTek for tuning solutions. With careful planning, your Evo X can meet—and safely exceed—the 400‑hp mark.