The 5.7-liter Hemi V8 found in the Dodge Challenger is a legendary powerplant that combines bold American muscle with modern engineering. Out of the box, it delivers solid performance and a signature exhaust note, but serious enthusiasts know that the car has hidden potential begging to be unlocked. Whether you're aiming for a more responsive daily driver, a capable track weapon, or a high-horsepower street machine, three foundational upgrades deliver the most impact: forged pistons, an MDS delete kit, and performance suspension springs. Each addresses a specific weakness in the factory setup, improving durability, throttle response, or handling. In this guide, we'll examine why these parts matter, what to look for when buying them, and how they work together to transform your Challenger's driving experience.

1. Pistons: Laying the Foundation for Power

The factory pistons in a stock 5.7 Hemi are cast units designed for reliability, low cost, and quiet operation. While adequate for the 370–375 horsepower the engine produces from the factory, cast pistons become a liability as soon as you add forced induction, nitrous, or a high-compression build. Upgrading to a set of aftermarket performance pistons is one of the smartest investments you can make for long-term durability and power potential.

Cast vs. Forged Pistons

The primary distinction in piston construction is between cast and forged. Cast pistons are made by pouring molten metal into a mold, which is inexpensive but leaves the material porous and less dense. Forged pistons, on the other hand, are formed under extreme pressure from a solid billet of aluminum, resulting in a much denser, stronger part. Forged pistons can withstand higher cylinder pressures, temperatures, and detonation events that would crack cast units. For any build targeting 500 horsepower or more, or for engines running boost, forged pistons are non-negotiable.

Compression Ratio Choices

Piston design directly controls compression ratio, which has a major effect on power characteristics. Most 5.7 Hemi engines run a static compression ratio between 9.6:1 and 10.5:1, depending on the year and application. Raising the ratio to 11.0:1 or higher with domed pistons can increase mid-range torque and peak horsepower, but requires careful tuning to avoid knock. For forced induction builds, a lower ratio (9.0:1 to 9.5:1) is often chosen to keep boost safe. Many aftermarket piston manufacturers like Mahle, CP-Carrillo, and Diamond Pistons offer 5.7 Hemi pistons in a range of compression heights and dome volumes, so you can match the exact ratio to your cam, heads, and power adder.

Weight and Reciprocating Mass

Lightweight pistons reduce reciprocating mass, which allows the engine to rev faster and free up parasitic drag. Most forged pistons are already lighter than factory cast units because they can be designed with thinner ring lands and shorter skirts thanks to the superior material strength. Pairing lightweight pistons with forged connecting rods further reduces inertia, improving throttle response and reducing bearing loads. Some builders report gains of 10–15 horsepower just from reducing rotating assembly weight, though the real benefit is in drivability and reliability at high RPM.

Installation and Machining Considerations

Swapping pistons is a bottom-end engine job that requires disassembling the short block. You'll need to have the block honed to match the new piston's clearance specifications, and the connecting rods should be resized or replaced. Many 5.7 Hemi owners choose to perform a full forged rotating assembly upgrade (pistons, rods, crankshaft) when the engine is already apart. While this increases the budget significantly, it future-proofs the build for 700+ horsepower. For the DIY enthusiast, expect to spend $1,500–$3,000 on a quality piston set and associated machine work. Professional installation can add another $1,000–$2,000 in labor.

2. MDS Delete Kits: Reclaiming Consistent Power Delivery

The Multi-Displacement System (MDS) is a fuel-saving feature found on many 5.7 Hemi engines. Under light load, the system deactivates the intake and exhaust valves on four of the eight cylinders, turning the V8 into a four-cylinder for better gas mileage. While that sounds good on paper, many Challenger owners find MDS intrusive, slow to react, and detrimental to the driving experience. MDS delete kits remove the system's functionality, or completely replace the lifters and solenoids with fixed components, providing full V8 operation at all times.

How MDS Works and Why It Is Problematic

MDS uses special lifters that can collapse and deactivate when oil pressure is routed through solenoids. The transition between four- and eight-cylinder modes happens in milliseconds, but it can cause a slight hesitation or lurch, especially during highway cruising or light acceleration. Over time, the MDS components can wear unevenly, leading to lifter failure and camshaft damage — a well-known issue on higher-mileage Hemi engines. Many owners report what they call "Hemi tick," which in some cases is traced to failing MDS lifters. By deleting the system, you remove these failure-prone parts and simplify the valvetrain.

What an MDS Delete Kit Includes

Most deluxe MDS delete kits come with: non-MDS lifters (fixed, non-collapsible), plug gaskets or blocking plates for the oil passages, and in some cases a non-MDS camshaft that doesn't have the extra lobes for the solenoids. Some kits are designed to work with the factory camshaft by using special sleeves or blocking the solenoid ports. The most reliable approach is a full swap to non-MDS lifters and a compatible camshaft, as this eliminates all future risk. Brands like Modern Muscle Xtreme (MMX) and Diablosport offer plug-and-play MDS delete solutions, often bundled with a tune to recalibrate the engine computer.

Tuning Requirements After MDS Delete

Once you remove MDS hardware, the PCM will throw a diagnostic trouble code (DTC) because it expects to see MDS solenoids and feedback. The only way to clear that is a custom tune that disables MDS control software. Many tuners also take the opportunity to adjust fuel and spark tables to take advantage of the improved valvetrain stability. Without a tune, the car may run in limp mode or have a check engine light. A handheld tuner from HP Tuners or Diablosport is a common companion to this upgrade. Expect to pay $300–$600 for the hardware kit and another $400–$600 for a custom dyno or remote tune.

Performance Benefits Beyond Reliability

While the primary motivation for MDS delete is reliability, the performance gains are noticeable. Throttle response becomes sharper because there is no delay when the engine transitions to full cylinder operation. The exhaust note also becomes more consistent, without the subtle change in tone when MDS engages. Some drivers report a small power increase — usually 5–10 horsepower — because the engine no longer has to manage the MDS oil circuits and can run a more aggressive cam profile. For those building high-horsepower Hemi engines, MDS delete is considered mandatory before adding boost or high-RPM camshafts.

3. Performance Springs: Dialing in Chassis Attitude and Grip

A muscle car's straight-line speed means little if the chassis can't handle corners effectively. The stock Challenger suspension is tuned for a comfortable ride, with soft springs and generous body roll. While fine for highway cruising, this setup hurts both lap times and driver confidence during aggressive driving. Upgrading to performance springs is the most cost-effective way to transform the Challenger's handling without a complete suspension overhaul.

Lowering Springs vs. Coilovers

Two main categories exist for spring upgrades: static lowering springs (with separate dampers) and coilover kits (integrated spring-and-damper units). Lowering springs are cheaper and easier to install — you simply swap them onto your existing shocks and struts. They typically lower the car 1.0–1.5 inches, reducing the center of gravity and compressing the suspension travel. Coilovers are more expensive but offer adjustable ride height, spring preload, and often damping force. For a dedicated street car, a quality set of lowering springs paired with good shocks (like Bilstein or Koni) is a fantastic value. For track use, coilovers from KW, H&R, or Eibach provide the adjustability needed to fine-tune corner balance.

Spring Rates and Ride Quality

Spring rate (measured in pounds per inch of compression) determines how stiff the suspension feels. Stock Challenger springs are in the 120–140 lb/in range, which is soft. A typical performance upgrade bumps this to 180–250 lb/in in the front and 150–200 lb/in in the rear. Higher spring rates reduce body roll and improve steering response, but they also transmit more road imperfections into the cabin. For a daily driver, a spring rate that's 30–40% stiffer than stock is a good balance. Brands like Eibach (Pro-Kit) and H&R (Sport Springs) offer rates that are aggressive enough for spirited driving without being punishing on rough roads.

Installation and Alignment

Replacing springs on a modern Challenger is a manageable weekend job if you have a spring compressor and basic tools. However, because the car uses a McPherson strut front suspension and a multi-link rear, you will need a professional alignment afterward. Lowering the car changes the camber and toe angles, and without adjustment, tires can wear unevenly. Many owners also add adjustable front control arms (like from BMR or Hotchkis) to restore proper geometry. Budget around $300–$600 for a quality set of lowering springs and $100–$200 for the alignment.

4. Complementary Upgrades That Multiply the Gains

The three upgrades above are powerful on their own, but their benefits are amplified when combined with a few complementary modifications. A cold air intake and a cat-back exhaust system free up airflow, letting the engine breathe easier with the new pistons and tune. A larger throttle body (80–90mm) improves throttle response, especially after MDS delete. If you have budget left, a camshaft swap can complement the forged pistons and MDS delete, boosting top-end power by 30–50 horsepower. Parts like a compression-matched camshaft from Comp Cams or Chevrolet Performance make a natural pairing with higher spring rates to control valve float.

5. Choosing a Reputable Builder or Parts Supplier

Not all aftermarket parts are created equal. For pistons, stick with established names like Mahle, CP-Carrillo, Wiseco, and Diamond. For MDS components, look for kits that come with genuine Mopar lifters or those manufactured by Delphi or Sealed Power. For springs, trust suspension specialists like Eibach, H&R, KW, or Swift. Work with a shop that has experience with Hemi engines — many performance rebuilders specialize in 5.7 and 6.4 Hemi builds. Online forums like ChallengerTalk and LXForums are good resources to vet parts and ask about real-world results.

6. Performance Testing and Dyno Results

Before and after dyno runs are a great way to quantify your upgrades. A typical forged piston swap plus a tune yields 10–20 horsepower over a stock bottom end with the same cam and heads, primarily from reduced pumping losses and the ability to run more timing. An MDS delete paired with a tune often shows 5–10 horsepower and a smoother torque curve. A quality set of lowering springs won't directly increase wheel horsepower, but they'll reduce 60-foot times by improving weight transfer and traction. Combined, these upgrades can shave 0.3–0.5 seconds off a quarter-mile time and significantly improve lap times on a road course.

Conclusion

The 5.7 Hemi Challenger is a platform with immense potential, and these three upgrades — forged pistons, MDS delete kits, and performance springs — form the foundation of any serious build. Pistons unlock the engine's strength to handle more power and revs. MDS delete eliminates a weak link in the valvetrain while sharpening throttle response. Springs transform the chassis from a floaty cruiser into a corner-carving machine. Individually they deliver noticeable improvements; together they create a cohesive, capable muscle car that is as rewarding on a back road as it is at the drag strip. Plan your build carefully, invest in quality parts, and don't skip the supporting modifications and professional tuning. Your Challenger will thank you with years of thrilling performance.