Unlock Hidden Horsepower in Your Dodge Stealth

The Dodge Stealth, a rebadged Mitsubishi GTO, has earned a loyal following among sports car enthusiasts for its aggressive styling and solid engineering. Whether you own a base model or a turbocharged VR‑4, the aftermarket community has developed proven upgrades that can dramatically increase power without requiring a second mortgage. With a budget of around $1,200, you can realistically add 50 or more horsepower to your Stealth, transforming it into a more thrilling machine for daily driving or track days. Below are the five most effective modifications to achieve that goal, each chosen for its value, ease of installation, and synergy with other parts.

Before diving into the upgrades, remember that every engine responds differently based on its condition, mileage, and existing modifications. Always perform a compression test and check for vacuum leaks before adding power. For in‑depth tuning resources, 3Si.org remains the definitive community forum for Stealth and 3000GT owners.

1. Performance Air Intake System

Improving the engine’s ability to breathe is the cheapest and simplest way to gain horsepower. The stock air intake system on the Dodge Stealth is restrictive, especially on later models with complex resonator boxes and snorkels. A performance cold air intake (CAI) or short ram intake reduces restriction and draws in cooler, denser air.

  • Gains: 5–10 horsepower on naturally aspirated Stealths; up to 15 horsepower on turbocharged VR‑4 models when combined with a well‑designed intake pipe.
  • Installation: A straightforward bolt‑on job requiring basic hand tools. Expect 1–2 hours if you’re handy; about 30 minutes on later models with simpler routing.
  • Cost: $200–$350 for a kit from brands like Injen, K&N, or a quality universal cone filter with custom piping. Some owners opt for a short ram style to avoid heat soak at low speeds, but a true CAI placed in the bumper duct offers better hot‑laps performance.
  • Synergy: Pairs well with an upgraded exhaust system (next section) by reducing backpressure on both intake and exhaust sides.

Tip: Avoid cheap oiled filters that can contaminate the mass airflow sensor (MAF). Use a dry filter or clean the MAF after installation. For a full walkthrough, Stealth316.com provides detailed guides for each engine variant.

2. High‑Performance Exhaust System

After improving intake flow, the next bottleneck is the exhaust. The Stealth’s factory exhaust uses small‑diameter pipes and restrictive catalytic converters that choke power, especially on turbocharged engines. A cat‑back or turbo‑back exhaust system (with a high‑flow cat or test pipe) can liberate significant horsepower.

  • Gains: 10–20 horsepower on non‑turbo models; 20–30 horsepower on turbos if you replace the downpipe and precat.
  • Installation: Moderate difficulty. You’ll need jack stands, penetrating oil for rusted bolts, and possibly an extra hand to align large sections. Expect 3–4 hours for a full exhaust swap.
  • Cost: $500–$800 for a quality cat‑back system from HKS, GReddy, or a custom mandrel‑bent setup. For the best value, consider a used system from forum classifieds.
  • Sound: The exhaust note becomes deeper and more aggressive; many owners report a drone at highway speeds, so consider a resonated midpipe if you drive long distances.

Important: Check local emissions laws before removing catalytic converters. A high‑flow cat retains legality while still providing a noticeable power increase. For detailed part comparisions, 3SX Performance stocks a wide range of Stealth‑specific exhaust components.

3. ECU Tune (Boost Controller for Turbo Models)

On modern vehicles, the engine control unit (ECU) governs fuel, spark, and boost. A tune (often called a “flash” or “chip”) custom‑adjusts these parameters to match your other upgrades. For the Stealth, options range from a simple boost controller (for VR‑4) to a full standalone ECU.

  • Gains: 10–20 horsepower from a boost controller alone (raising boost to safe levels around 12–14 psi); 20–40 horsepower from a proper dyno tune with supporting mods.
  • Installation: A manual boost controller costs $50 and installs in minutes. For an ECU tune, you can mail your ECU to specialists like Chrysler Stealth ECU Tuning or use a piggyback like the AEM FIC. DIY tuning requires careful research.
  • Cost: $50–$200 for boost controllers; $300–$500 for a socketed chip tune from known tuners. A standalone ECU can exceed $1,000, so stick with budget options first.
  • Synergy: Always tune after installing intake and exhaust; the ECU will then fully utilize the increased flow.

Caution: Raising boost without addressing fuel delivery can cause knock and engine damage. Ensure your fuel pump is in good shape and consider a wideband oxygen sensor to monitor air‑fuel ratios. Forum resources like Stealth316’s boost control guide are invaluable.

4. Upgraded Intercooler (Turbo Models)

For the twin‑turbo VR‑4, the stock intercoolers are small and prone to heat soak after a few pulls. A larger front‑mount intercooler (FMIC) or upgraded side‑mounts dramatically reduce intake air temperatures, allowing the engine to make more power safely.

  • Gains: 10–15 horsepower after the car warms up; more importantly, it prevents power loss on hot days and during repeated runs.
  • Installation: Moderate to difficult. You’ll need to remove the front bumper cover and trim some plastic behind the bumper. FMIC kits require cutting the crash bar slightly on some years. Expect 4–6 hours.
  • Cost: $300–$500 for a quality FMIC kit from brands like Spearco or a universal unit with custom piping. Used kits are common for around $200.
  • Synergy: An upgraded intercooler works hand‑in‑hand with a higher boost setting from an ECU tune or boost controller, maximizing power without knocking.

Note: Non‑turbo Stealth owners can skip this upgrade. For VR‑4 owners, consider upgrading the blow‑off valves while you’re there — they tend to leak at higher boost levels.

5. Lightweight Flywheel

The stock flywheel on the Dodge Stealth is heavy, designed for smooth engagement at the expense of throttle response. Replacing it with a lighter unit (9–12 lb) reduces rotational inertia, allowing the engine to rev up and down much faster.

  • Gains: While not a direct horsepower increase, a lightweight flywheel can shave 0.3–0.5 seconds off 0–60 times and make the car feel much more responsive. Dyno numbers won’t change, but seat‑of‑the‑pants gains are significant.
  • Installation: Major job requiring transmission removal. Rated as advanced; you’ll need a transmission jack, clean workspace, and a torque wrench. Expect 6–8 hours if you’re experienced.
  • Cost: $200–$300 for a chromoly flywheel from Fidanza or ACT. If you’re doing a clutch replacement, this is the perfect time to install it.
  • Downside: Slightly more chatter from the transmission and a bit harder to launch smoothly. Most owners consider it worth the trade‑off.

Pro tip: Pair the lightweight flywheel with a stage 1 or stage 2 clutch kit. The stock clutch may slip under increased power, especially after an ECU tune. A budget clutch from AMS Performance or similar can handle the extra torque.

Putting It All Together: How to Stay Within $1,200

To hit your horsepower goal without exceeding $1,200, prioritize the upgrades that give the best bang for the buck. Here’s a sample budget build order:

  1. Performance air intake ($250) — quickest 10 hp.
  2. Boost controller + used intercooler ($250–$350) — for turbo models, this adds 15–25 hp.
  3. Cat‑back exhaust ($500–$600) — another 10–15 hp and a great sound.
  4. Lightweight flywheel ($200–$300 used) — only if you can install it yourself or have a friend help.

This combination totals around $1,200 and can reliably produce 50–60 horsepower on a VR‑4, or 40–50 on a naturally aspirated Stealth. If you have a little more budget, a basic ECU tune (chip) can be added for another $300, pushing you beyond 60 hp.

Remember to upgrade the fuel pump ($100) and consider an adjustable fuel pressure regulator if you run more than 14 psi of boost. A wideband air‑fuel ratio gauge is cheap insurance against leaning out.

Beyond the 5 Upgrades: Maintenance First

Before spending money on power, ensure your Stealth is mechanically sound. Replace spark plugs (NGK BKR7E‑11), wires, and perform a timing belt service if it’s due. A smooth‑running engine will respond better to mods and live longer. Also, verify that your cooling system is in good shape — a 60K factory radiator can’t handle extra heat from a tune.

For those on a strict budget, consider buying used parts from the Dodge Stealth Owners Facebook group or local car meets. Many enthusiasts upgrade and sell their old intake, exhaust, or flywheel at a fraction of retail cost.

Final Thoughts: Enjoy the Process

The Dodge Stealth is a rewarding platform to modify. With careful planning and a $1,200 budget, you can build a car that not only feels faster but is genuinely quicker in the quarter mile or on backroads. Stick to the upgrades outlined above, invest in quality parts, and don’t forget basic maintenance. The end result will be a unique, driver‑focused sports car that punches well above its weight.

Looking for more? Check out 3SX’s power bundles which combine several of these parts at a discount.