The 6.4 Hemi: A Platform Built for Performance

The 6.4-liter Hemi V8 (392 cubic inches) is one of the most revered engines to come out of Stellantis. Found in the Dodge Challenger R/T Scat Pack, Charger Scat Pack, Durango SRT, and Jeep Grand Cherokee SRT, this naturally aspirated 392 Hemi delivers around 485 horsepower and 475 lb-ft of torque from the factory. That’s an impressive baseline, but for many enthusiasts, it’s just the starting point. The 6.4 Hemi responds exceptionally well to bolt-on modifications, forced induction, and optimized fuel delivery and exhaust flow.

Choosing the right components and brands can make the difference between a reliable 550-wheel-horsepower street car and a finicky, heat-soaked project. In this guide, we dive deep into three of the most respected brands in the 6.4 Hemi aftermarket: AMS Performance, RIPP Superchargers, and Borla Exhaust Systems. We’ll cover their key products, real-world performance gains, installation complexity, and how each fits into a comprehensive build plan.

AMS Performance: Precision Tuning and Thermal Management

AMS Performance, based in Illinois, is a household name among high-performance enthusiasts. While known for building record-breaking Nissan GT-Rs and Audis, AMS has pivoted heavily into the Mopar world with a dedicated line of Hemi upgrades. Their focus is not just on peak power but on sustained performance through superior thermal management and calibration.

AMS Alpha Series Cold Air Intake

One of the first upgrades that almost every 6.4 Hemi owner considers is a cold air intake. The AMS Alpha Series intake replaces the restrictive factory air box with a high-flow, sealed system. It features a silicone elbow, a large conical dry filter, and a heat shield that draws air from outside the engine bay. The result is a consistent intake air temperature drop of 15–20°F under load compared to the stock setup. This alone can unlock 10–15 wheel horsepower on a tuned 6.4, with a noticeable improvement in throttle response.

High-Performance Intercooler and Heat Exchanger Upgrades

For supercharged or forced-induction builds (including those using factory-supercharged Hellcat swaps), AMS manufactures aluminum intercoolers and high-flow heat exchangers. Their heat exchanger for the Jeep Grand Cherokee SRT and Dodge Durango SRT increases coolant capacity by 40% and uses a more efficient tube-and-fin core. This keeps charge air temperatures low, preventing the power loss that occurs when the ECU pulls timing due to heat soak. For naturally aspirated 6.4 builds, AMS also offers an oil cooler kit that helps maintain consistent oil temps during track days or aggressive driving.

Custom Tuning via AMS

AMS provides remote tuning using the HP Tuners platform. Their calibrations are tailored for your specific modifications, whether it’s just an intake and exhaust or a full camshaft and header setup. A custom AMS tune for a 6.4 Hemi with bolt-ons typically yields gains of 30–40 wheel horsepower and similar torque increases. The tuners focus on optimizing the air/fuel ratio, spark timing, and transmission shift behavior (on 8HP70 automatics) to deliver a smooth but aggressive power curve. Many owners report that the car feels significantly stronger in the mid-range and pulls harder to redline.

For more information on their complete product line for the 6.4 Hemi, visit AMS Performance.

RIPP Superchargers: Forced Induction for the 6.4 Hemi

If you’re looking to make a serious jump in power — from 485 horsepower to 700 or even 800 wheel horsepower — a supercharger is the traditional route. RIPP Superchargers (RIPP stands for Really Incredible Performance Products) has been engineering centrifugal supercharger kits for Hemi engines for over a decade. Their kits are designed specifically for the 6.4 liter, with no major fabrication required.

RIPP Supercharger Kit Overview

The RIPP Gen 3 supercharger kit for the 6.4 Hemi includes a Vortech V3 Si trim centrifugal supercharger, a custom cast aluminum intake manifold with integrated charge cooler, a high-flow fuel pump booster, and a complete calibration delivered via handheld tuner or remote dyno tuning. The kit is available for both the Challenger/Charger Scat Packs and the Jeep Grand Cherokee SRT / Durango SRT. Power output depends on boost level and supporting mods, but the typical stage 1 kit on a stock engine runs 6–7 psi and produces around 580–620 wheel horsepower on 93 octane. With a stage 2 upgrade (larger intercooler, injectors, and pump), numbers climb to 680–720 whp on pump gas, and over 800 whp on E85.

Installation and Maintainability

RIPP designs their kits with the weekend mechanic in mind. The supercharger mounts to the front of the engine, driven by the accessory belt. The charge cooler is integrated into a replacement intake manifold that flows better than stock. The installation does require removing the factory intake manifold, radiator shroud, and intercooler, but the kit uses a detailed instruction manual and all necessary hardware. Most owners complete the install over a weekend. Because the Vortech supercharger is a centrifugal design, it doesn’t produce the low-end boost of a positive-displacement blower — instead, it builds power progressively as RPM rises. This makes the car very streetable and preserves driveline life.

Tuning and Reliability

RIPP provides a base calibration via DiabloSport or HP Tuners. For best results, many owners opt for a custom dyno tune at a RIPP-authorized shop. The factory 6.4 Hemi bottom end (forged rods and pistons in earlier years, powdered metal rods in later models) can handle up to about 650 wheel horsepower reliably. Beyond that, forged pistons and rods are recommended. RIPP offers optional fuel system upgrades and a larger heat exchanger to support higher boost levels. Their customer support is notable — they answer technical questions quickly and have a strong presence on the RIPP website and forums like LXForums.

For a firsthand account of a RIPP supercharger installation on a 6.4 Challenger, check out this user review thread on DriveSRT Forum (external forum).

Borla Exhaust Systems: Sound and Flow Perfection

Any performance build, whether naturally aspirated or supercharged, needs a quality exhaust system. Borla has been building exhausts for over 40 years and is widely regarded as the gold standard for American V8s. Their stainless steel construction, patented technology, and meticulous sound tuning make them a go-to for Hemi owners who want the right tone and performance gains.

Borla Cat-Back Systems for 6.4 Hemi

Borla offers three main cat-back exhaust families for the 6.4-equipped vehicles: A-tak, S-Type, and Tour. The A-tak is the most aggressive, with a distinctive “rev-matching” burble and a loud, race-inspired note. The S-Type is a performance-oriented system with a deep muscle car tone but doesn’t drone on the highway. The Tour is the mildest — still louder than stock but refined for daily driving. All three systems are CNC-mandrel bent from T-304 stainless steel and are backed by Borla’s million-mile warranty. Typical peak power gains from a cat-back system on a tuned 6.4 Hemi are in the range of 8–12 wheel horsepower, but the real advantage is weight savings (up to 15–20 lbs over the factory unit) and reduced backpressure.

Header and Mid-Pipe Options

For the full exhaust system upgrade, Borla also produces long-tube headers for the 6.4 Hemi (available through their Borla Header division and partner manufacturers). Pairing a set of long-tubes with a Borla cat-back and a high-flow catted or catless mid-pipe unlocks the full potential of a camshaft upgrade or supercharger kit. A complete Borla header-back exhaust system can add 25–35 horsepower to a naturally aspirated 6.4 with a custom tune, along with a significantly more aggressive sound.

Why Choose Borla?

Unlike cheaper exhaust brands, Borla invests heavily in acoustic engineering to eliminate drone and undesirable frequencies. Their patented “Reflective Sound Cancellation” uses diffuser tubes at the tailpipe tips to reduce unwanted rasp while preserving the rich V8 rumble. The quality of materials ensures the system will outlast the car — raw T-304 stainless steel resists corrosion and discoloration far better than 409 stainless. For the 6.4 Hemi owner who cares about fit, finish, and sound refinement, Borla is an easy choice.

Explore the full selection of cat-back systems for your specific 6.4 Hemi vehicle at Borla’s official site.

Building a Cohesive 6.4 Hemi Setup

It’s important to understand that these three brands complement each other beautifully. For a naturally aspirated street build, a common progression is:

  1. Cold Air Intake: AMS Alpha Series to reduce intake temps and add a few horsepower.
  2. Exhaust: Borla S-Type or ATAK cat-back to free up exhaust flow and improve sound.
  3. Tuning: AMS custom tune (or HP Tuners remote tune) to optimize air/fuel ratios.

This combination can net 380–400 wheel horsepower (up from ~370 whp stock) on a Challenger Scat Pack, with a much more responsive throttle and a thrilling soundtrack.

For forced induction applications, the synergy changes:

  • Start with a RIPP Supercharger Kit as the foundation for big power.
  • Upgrade the heat exchanger and charge cooling (AMS) to keep IATs in check.
  • Add a Borla cat-back (or even a full header-back system) to support high-flow scavenging.
  • Finally, use a RIPP-provided or AMS custom tune for fuel and timing.

With this combo, 700 wheel horsepower is achievable on pump gas, and 800+ on E85, while maintaining daily drivability. The centrifugal supercharger doesn’t hit hard down low, but the Borla exhaust keeps the car sounding menacing at all RPMs.

Common Pitfalls and Pro Tips

  • Don’t skip the tune: Many 6.4 owners install a cold air intake and exhaust without a tune, leaving 20–30 horsepower on the table. The stock ECU will not take full advantage of the improved airflow.
  • Heat management is critical: The 6.4 Hemi generates a lot of heat, especially in heavy traffic or during autox. AMS’s intercooler and oil cooler upgrades are worth the investment, particularly for supercharged or track-driven cars.
  • Fuel system limits: The factory fuel injectors and pump on a 6.4 Hemi are adequate for naturally aspirated mods, but with a supercharger beyond stage 1, you’ll need larger injectors and a BAP (boost-a-pump) or in-tank pump upgrade. RIPP kits include fuel system components, but verify compatibility with your year model.
  • Transmission tuning: The 8HP70 automatic used in most 6.4 Hemi vehicles is robust, but it needs recalibration under high torque. Both AMS and RIPP include transmission tuning in their packages, but if you go with a third-party tuner, insist on a full trans tune to prevent premature clutch wear.

Frequently Asked Questions

Can I combine a RIPP supercharger with an AMS intercooler?

Yes. RIPP supercharger kits use a charge cooler integrated into the intake manifold, but the system still relies on a front-mounted heat exchanger. The AMS high-performance heat exchanger can replace the RIPP unit for better cooling, and this is a common upgrade for track-focused cars. Confirm with technical support at both companies to ensure flow rate compatibility.

Will a Borla exhaust void my factory warranty?

No aftermarket exhaust part automatically voids a warranty. The Magnuson-Moss Warranty Act protects consumers, but if a dealership can prove that the aftermarket part caused a failure (e.g., an improperly installed system that causes heat damage to a sensor), that specific repair may be denied. Borla exhausts are designed to be direct replacements with no modification to the emissions system (if you keep cats), so warranty issues are rare.

Which brand offers the best support for DIY installers?

All three brands offer detailed instructions and phone/email support. RIPP probably has the most comprehensive installation guide for their supercharger kit, including videos on their website. AMS also provides good support for their intake and intercooler installations. Borla exhausts are generally bolt-on and require no specialized tools beyond basic hand tools.

Final Thoughts

AMS Performance, RIPP Superchargers, and Borla Exhaust Systems each bring unique strengths to the 6.4 Hemi aftermarket. AMS excels in custom tuning and thermal management, making your engine run stronger and cooler. RIPP provides the most comprehensive centrifugal supercharger solution for big power gains. Borla delivers the best-sounding, highest-quality exhaust systems that complement any build level. By choosing components from these proven brands and integrating them correctly with proper tuning, you can transform your 6.4 Hemi into a reliable, exhilarating performer that stands out on the street and at the track.