Why These Upgrades Matter for Your Evo 9

The Mitsubishi Lancer Evolution IX remains a cornerstone of turbocharged performance, revered for its 4G63 engine and advanced all-wheel-drive system. As boost levels climb, two weak points often emerge: the factory intercooler’s heat capacity and the recirculating blow-off valve’s ability to handle higher airflow. Replacing these with an HKS Super SQV sequential blow-off valve and a larger intercooler addresses both issues, improving throttle response and reducing intake air temperatures. This guide provides a detailed, itemized cost breakdown, covering parts, labor, and the hidden expenses that can arise during installation.

Understanding the Upgrades

HKS Super SQV Blow-Off Valve

The HKS Super SQV (Sequential Blow-Off Valve) is a distinct upgrade from the standard recirculating valve found on the Evo 9. It uses a pull-type, spring-and-piston design that opens in two stages: a primary port for low boost and a secondary port under high boost. This allows the valve to vent excess boost pressure to atmosphere without causing compressor surge, which can degrade the turbocharger’s compressor wheel over time. The result is a distinctive “psshh” sound that many enthusiasts prefer, but the real benefit is reduced turbo lag between gear changes. For those running higher boost with an upgraded turbo or larger injectors, the stock Mitsubishi valve often leaks under sustained pressure, making the HKS an essential reliability component.

Upgraded Intercooler

An upgraded intercooler is one of the most effective bolt-on modifications for the Evo 9. The factory intercooler is a bar-and-plate unit that works well at stock power levels but becomes a thermal bottleneck as boost and airflow increase. Aftermarket intercoolers use a larger core, more efficient fin design, and thicker end tanks to reduce pressure drop while keeping charge air temperatures closer to ambient. Cooler, denser air increases oxygen content in the combustion chamber, allowing more fuel to be burned and producing more power. Additionally, a better intercooler helps prevent detonation (knock) under high load, which is critical for tuning reliability. Typical gains from a quality intercooler alone are 15–25 whp on a tuned Evo 9, with further improvements when combined with a blow-off valve that can handle the increased flow.

Itemized Cost Breakdown

Below is a detailed cost breakdown for purchasing and installing both upgrades. Prices are based on current market averages from reputable retailers and professional shops. Actual costs may vary depending on location, shipping, and chosen brands.

HKS Super SQV Blow-Off Valve Costs

Item Cost Range Notes
HKS Super SQV (basic kit) $250 – $350 Includes valve, spring, and adapter plate. SSQV4 model is newer and slightly more expensive.
Flange kit or weld-on fitting $30 – $60 Some kits include a universal flange; dedicated Evo 9 kits may require an extra adapter.
Installation labor (professional) $100 – $200 Simple bolt-on; most shops charge 1–2 hours at $100–$150/hour.
Subtotal (HKS Super SQV upgrade) $380 – $610 Includes all parts and labor.

Upgraded Intercooler Costs

Item Cost Range Notes
Intercooler core $400 – $1,200 Range covers entry-level (e.g., CX Racing) to premium (ETS, AMS, Garrett). Core size matters: thicker cores cost more.
Piping kit (if needed) $150 – $400 Often required if the intercooler uses a different inlet/outlet configuration. Full silicone hose kits add cost.
Installation labor $200 – $500 Front bumper removal, test fit, possible trimming of the crash beam. Shop rates vary.
Tuning / recalibration (recommended) $300 – $600 To take full advantage of cooler intake temps, a tune is strongly advised. Not mandatory but recommended.
Subtotal (intercooler upgrade) $1,050 – $2,700 Includes core, piping, install, and tune.

Total Estimated Cost for Both Upgrades

Combining both projects (including professional installation and a tune for the intercooler) yields the following range:

  • Low-end total: $1,430 (budget intercooler, basic BOV kit, self-install or friends’ help)
  • Mid-range total: $2,000 – $2,500 (quality intercooler like ETS, HKS SSQV, pro install, no tune)
  • High-end total: $3,310 – $3,500 (premium intercooler with full piping, HKS SSQV4, pro install, custom tune)

Factors That Influence Costs

Brand Selection

Intercooler brands vary significantly in quality. Premium options like Extreme Turbo Systems (ETS) and AMS Performance use high-density cores with minimal pressure drop, often costing $800–$1,200. Budget brands (e.g., SpeedFactory, Godspeed) offer cores for $400–$600 but may require additional work for fitment. The HKS Super SQV is less variable; the HKS website lists the SSQV for around $300. Counterfeit valves exist; buy from authorized dealers to avoid issues.

Installation Complexity

Intercooler installation on an Evo 9 typically requires removing the front bumper, headlight housing, and radiator support. Some aftermarket intercoolers require trimming the crash beam or relocating the AC condenser. If you tackle the job yourself, you save $200–$500 but risk breaking clips or misaligning the cooling system. Blow-off valve installation is far simpler—usually a direct replacement on the intercooler pipe (if using the proper flange). Factor in the cost of any specialty tools (e.g., socket set, torque wrench).

Tuning Requirements

While the blow-off valve does not require a tune (though it may alter the MAF signal if fully vented to atmosphere on a recirculating car), the intercooler dramatically changes intake air density. On an Evo 9, the factory ECU can compensate to some extent via fuel trims, but to unlock the full power potential—often 20–40 whp depending on boost—a professional tune on a dyno or via an ECU flash (e.g., EcuTek, COBB Accessport) is recommended. A tune adds $300–$600 to the total but is arguably the most cost-effective power adder per dollar.

DIY vs. Professional Installation

DIY Pros and Hidden Costs

Many experienced Evo owners install both upgrades themselves. Intercooler installation is a weekend project for someone comfortable with basic mechanical work. You'll need a jack, jack stands, trim tools, and possibly a Dremel for minor trimming. DIY saves $300–$700 in labor but exposes you to costs like broken connectors, replacement bolts, or coolant refill. Additionally, if you do not have a vacuum pump to bleed the cooling system after removing the radiator, you may end up with air pockets. Buying a service manual (e.g., Evo 9 factory service manual) can help avoid mistakes.

When to Hire a Professional

If you are not comfortable removing the front bumper or cutting into a crash beam, professional installation is wise. Look for a shop that specializes in Mitsubishi Evos or turbocharged imports. Rates vary from $100/hour (independent shop) to $175/hour (dealership or specialty tuner). Ask for a fixed quote—some shops charge extra if they encounter rusted bolts or non-OEM components. For the intercooler, plan on 3–5 hours labor; for the blow-off valve, 1 hour.

Additional Considerations

Warranty and Insurance Implications

Both modifications may void certain factory warranties on the engine and drivetrain if a failure occurs. Check with your dealer or warranty provider before installing. Additionally, some insurance companies classify turbo upgrades and blow-off valves as “performance modifications,” which can raise premiums by 5–20%. It is advisable to disclose the upgrades to your insurer and note them on your policy to avoid claim disputes.

Performance Gains – Realistic Expectations

With a quality intercooler and a properly tuned blow-off valve, an Evo 9 with a boost controller set to 22–24 psi (stock turbo) can see 330–350 whp, up from the factory 260–280 whp. The intercooler alone accounts for about 15–25 whp; the BOV contributes indirectly by maintaining boost stability. Throttle response improves noticeably between shifts, and heat soak (power loss after repeated pulls) is significantly reduced. On a dyno, the difference in intake air temperatures can be 20–40°F lower at the end of a third-gear pull.

Ongoing Maintenance

An aftermarket blow-off valve requires periodic cleaning of the piston and spring area—every 10,000 miles or if you notice sticky operation. Use only silicone grease recommended by HKS. The intercooler core should be checked for debris (bugs, rocks) that can block airflow; a gentle wash with a low-pressure hose is sufficient. Inspect couplers and clamps for looseness annually; boost leaks are a common failure point after an intercooler upgrade.

Final Thoughts

Investing in an HKS Super SQV blow-off valve and an upgraded intercooler transforms the Evo 9 into a more responsive, cooler-running, and powerful machine. The total cost ranges from roughly $1,400 on a tight budget to over $3,300 for a premium, professionally installed setup with tuning. Prioritize quality components—especially the intercooler—since a poorly designed core can create more backpressure than the stock unit. If you plan to push beyond 350 whp in the future, consider a bar-and-plate core from a reputable brand like ETS or AMS that supports 500+ whp. The HKS Super SQV will continue to serve at those levels, making this combination a strong foundation for any Evo 9 build. Always source parts from authorized retailers, and do not skip the tune if you want to realize the full performance benefit safely.