Best Mods for a Stock 5.7 HEMI: A Beginner's Guide

Why Mod Order Matters

You just picked up a 5.7L HEMI-powered Ram, Challenger, Charger, or 300—and now you're ready to wake it up. The temptation is real: scroll through parts catalogs, add everything that looks cool to your cart, and bolt it all on in a single weekend. But here's the truth that experienced builders learn the hard way: the order you install mods matters just as much as the mods themselves.

The Gen III 5.7L HEMI is a remarkably capable platform straight from the factory, producing anywhere from 345 to 395 horsepower depending on year and application. But Chrysler engineers tuned it conservatively—balancing fuel economy, emissions compliance, and broad drivability. That means there's real power hiding in your HEMI, waiting to be unlocked with the right approach.

The Bottleneck Principle

Think of your engine as a system of interconnected pathways. Air comes in through the intake, mixes with fuel, combusts, and exits through the exhaust. The factory ECU manages all of it. If you upgrade just one piece without addressing the others, you've simply moved the bottleneck—not eliminated it.

• Intake without exhaust: You're shoving more air in, but the engine struggles to push spent gases out efficiently
• Exhaust without tuning: You've improved flow, but the factory tune doesn't know how to take advantage of it
• Tuning without hardware: A tune can optimize what you have, but it can't create airflow that isn't there

The goal is to build a balanced combination where each upgrade complements the others. When done right, the whole becomes greater than the sum of its parts.

Setting Realistic Expectations

Let's be honest about what bolt-on modifications can achieve. A well-executed intake, exhaust, and tune combination on a stock-internals 5.7L HEMI will typically net 25–50 rear-wheel horsepower—enough to feel a meaningful difference in throttle response, pull, and sound without sacrificing reliability or daily drivability.

That might not sound like headline-grabbing numbers, but consider this: those gains come without opening the engine, without upgrading fuel systems, and without voiding your powertrain warranty (depending on your dealer relationship and specific parts). It's the smart, sustainable path that keeps your HEMI happy for hundreds of thousands of miles.

Stage 1: Intake & Throttle Body

The factory airbox on your 5.7L HEMI is designed to be quiet, emissions-compliant, and effective across a wide range of conditions. It does its job—but it's not optimized for performance. That's why intake upgrades are the most popular first mod for HEMI owners: they're affordable, easy to install, and deliver immediate results you can feel and hear.

Cold Air Intakes: Your First Power Adder

A quality cold air intake (CAI) replaces the restrictive factory airbox with a free-flowing filter and mandrel-bent tubing that pulls cooler air from outside the engine bay. Cooler air is denser, which means more oxygen molecules per combustion cycle—and more oxygen means more power.

Expect gains in the range of 8–15 horsepower from a cold air intake alone, with improvements in throttle response that you'll notice immediately. The enhanced intake sound is a bonus—a deeper, more aggressive growl under acceleration that reminds you there's a HEMI under the hood.

When shopping for a cold air intake, look for these features:

• Mandrel-bent aluminum tubing: Smooth interior walls reduce turbulence and improve airflow
• Heat shield or enclosed airbox: Isolates the filter from engine bay heat, keeping intake temps low
• High-flow reusable filter: Oiled cotton gauze filters (like those from K&N) offer excellent filtration with superior flow
• Proper MAF sensor fitment: The intake tube must position the mass airflow sensor correctly to avoid drivability issues

Throttle Body Upgrades

The throttle body is the gateway between your intake and the engine's intake manifold. The factory 5.7L HEMI throttle body measures approximately 80-85mm depending on application—adequate for stock power levels, but a potential restriction as you add other mods.

Upgrading to a larger throttle body (87-90mm) improves airflow capacity and can sharpen throttle response, particularly at wide-open throttle. On a stock engine with just an intake, a throttle body upgrade alone won't add huge numbers—perhaps 5–10 horsepower. But it removes a future bottleneck and pairs perfectly with intake and exhaust work.

Keep in mind that throttle body upgrades typically require a tune to recalibrate the throttle position tables. This is another reason why saving your tune for last makes sense—you can calibrate for all your hardware changes at once.

Recommended Intake Upgrades

For Ram 1500/2500/3500 trucks (2009–2018), the K&N 77 Series Cold Air Intake is an excellent choice, featuring mandrel-bent aluminum tubing with a polished finish and an oversized oiled cotton filter. K&N estimates gains of 10+ horsepower and 12+ lb-ft of torque—solid numbers for a bolt-on part.

For Charger owners (2011–2020), the Volant Cold Air Intake delivers with its custom-engineered filter box that isolates intake air from engine bay heat, plus ultra-durable silicone connectors built to last.

Installation Difficulty: Easy

Cold air intake installation is a true beginner-friendly job. Most kits require only basic hand tools and can be completed in 30–60 minutes in your driveway. It's the perfect confidence-builder before tackling more involved upgrades.

Stage 2: Exhaust Upgrades

Once you've improved how your 5.7L HEMI breathes in, it's time to address how it breathes out. The factory exhaust system is engineered for noise compliance, emissions standards, and cost-effective manufacturing—not maximum flow. Upgrading your exhaust is where you'll find some of the most satisfying gains: real power you can feel and a sound that announces your HEMI's presence.

Exhaust upgrades come in stages, and understanding what each component does will help you build a system that matches your goals and budget.

Cat-Back Exhaust: The Foundation

A cat-back exhaust replaces everything from the catalytic converters rearward—mid-pipes, mufflers, and tailpipes. This is the most popular exhaust upgrade for good reason: it's emissions-legal in all 50 states, relatively easy to install, and delivers immediate improvements in both power and sound.

Quality cat-back systems use mandrel-bent tubing (typically 2.5" to 3" diameter) that flows far better than the crush-bent factory pipes. Expect gains of 10–20 horsepower depending on the system, with improved throttle response throughout the RPM range.

When choosing a cat-back, consider your priorities:

• Aggressive sound: Straight-through muffler designs (like chambered or bullet-style) maximize volume and growl
• Refined tone: Louvered or baffled mufflers deliver a deep rumble without excessive drone on the highway
• Maximum flow: Larger diameter piping (3") moves more exhaust gases but may sacrifice some low-end torque

Mid-Pipes and Resonator Deletes

The factory mid-pipe section often includes resonators—chambers designed to cancel specific sound frequencies and reduce cabin drone. Replacing the mid-pipe with a performance unit or eliminating the resonators opens up exhaust flow and amplifies the HEMI's natural rumble.

Mid-pipe upgrades are often paired with cat-back systems for a complete transformation. If you're building in stages, a cat-back first followed by a mid-pipe later is a logical progression.

Headers: The Ultimate Exhaust Upgrade

The factory exhaust manifolds are cast iron units that prioritize durability and heat retention over flow. Long-tube headers replace these restrictive manifolds with tuned-length primary tubes that scavenge exhaust gases more efficiently, dramatically improving power across the entire RPM range.

Headers are a more advanced upgrade—installation requires more time, tools, and often some creative problem-solving. They also typically require a tune to address the oxygen sensor placement changes. But the rewards are significant: 15–30+ horsepower from headers alone, with even greater gains when combined with a proper tune.

For most beginners, headers are a "later stage" upgrade. Start with your cat-back, add your tune, and save headers for when you're ready to take your build to the next level.

What to Expect: Sound and Power

A well-chosen exhaust system transforms the 5.7L HEMI's character. The factory exhaust mutes much of the engine's natural aggression—uncorking it reveals the lopey, muscular rumble that made HEMI engines legendary. Combined with your intake upgrades, you'll have a vehicle that sounds as good as it performs.

Installation Difficulty: Moderate

Cat-back exhaust installation is a solid weekend project for a DIYer with basic tools, a jack, and jack stands. Most systems use clamp or bolt-on connections to the factory catalytic converters. Budget 2–4 hours for a first-time install. Headers are more involved and often best left to an experienced shop unless you have lift access and prior exhaust experience.

Stage 3: Tuning

You've bolted on a cold air intake. You've installed a cat-back exhaust. Your 5.7L HEMI sounds incredible and feels a bit more responsive—but here's what most beginners don't realize: you're leaving power on the table. The factory ECU has no idea you've made these changes. It's still running the same conservative fuel and timing maps it left the factory with.

This is where tuning comes in. A proper tune recalibrates your engine's computer to take full advantage of your hardware upgrades—and it's often the single most impactful modification you can make.

Why Tuning Matters

Your HEMI's Powertrain Control Module (PCM) manages hundreds of parameters: fuel delivery, ignition timing, transmission shift points, throttle response curves, and more. From the factory, these settings are deliberately conservative to account for low-quality fuel, extreme weather conditions, and the needs of the average driver who never pushes past 4,000 RPM.

A performance tune optimizes these parameters for your specific combination of parts:

• Air/fuel ratio adjustments: Optimized fueling for your improved intake airflow
• Ignition timing advance: More aggressive timing (safely) extracts more power from each combustion event
• Throttle response mapping: Sharper, more immediate response to your right foot
• Transmission tuning: Firmer shifts, optimized shift points, and reduced "hunting" between gears
• Speed limiter and rev limiter adjustments: For off-road or track use where applicable

The result? Expect an additional 15–25 horsepower from tuning alone on a bolt-on 5.7L HEMI—sometimes more. Combined with your intake and exhaust, a quality tune brings your total gains into the 40–50+ horsepower range.

Handheld Tuners: Power in Your Hands

The most popular tuning solution for HEMI owners is a handheld tuner—a device that plugs into your OBD-II port and allows you to flash new calibrations directly to your PCM. These devices offer pre-loaded tunes optimized for common modifications, plus the ability to load custom tunes from professional calibrators.

DiabloSport is the industry leader for HEMI tuning, with devices specifically engineered for Chrysler/Dodge/Jeep/Ram applications. Their tuners offer:

• Pre-loaded performance tunes: Ready-to-flash calibrations for 91 and 93 octane fuel
• Custom tune support: Load tunes from professional calibrators for your exact build
• Datalogging: Monitor engine parameters in real-time to verify your tune is dialed in
• Diagnostic capability: Read and clear trouble codes without a trip to the dealer
• Stock restore: Return to your factory calibration anytime—essential for dealer visits or selling the vehicle

The DiabloSport inTune i3 Platinum is an excellent choice for 5.7L HEMI owners. It covers the full range of HEMI-powered vehicles from 2005–2023 and supports both pre-loaded and custom tuning. For those wanting to dive deeper into datalogging and diagnostics, it's a complete solution in one device.

When to Tune: Timing Is Everything

Here's the strategic reason we recommend tuning as Stage 3, not Stage 1: you only want to tune once. Every time you add a significant modification, your tune should be updated to account for it. If you tune after your intake, then add exhaust, you'll need another tune. Then if you add a throttle body, you'll need yet another.

By completing your bolt-on hardware first—intake, exhaust, throttle body—and then tuning for the complete package, you get the best results with a single calibration. This saves money and ensures your tune is optimized for everything working together.

A Note on MDS (Multi-Displacement System)

Many 5.7L HEMI owners choose to disable MDS—the cylinder deactivation system that shuts down four cylinders during light-load cruising. While MDS is great for fuel economy, some owners experience lifter tick or simply prefer the consistent V8 feel of all eight cylinders firing at all times.

Disabling MDS requires a tune—you can't do it with hardware alone. This is another reason a quality handheld tuner is a worthwhile investment: it gives you control over features like MDS that would otherwise require a dealer visit or aftermarket module.

Installation Difficulty: Easy

Flashing a tune is the easiest "installation" you'll ever do. Plug the tuner into your OBD-II port (under the dash), follow the on-screen prompts, and wait 10–15 minutes while the new calibration writes to your PCM. The hardest part is resisting the urge to immediately go test your newfound power.

The Smart Upgrade Path

Now that you understand the three stages of basic bolt-on modifications, let's put it all together into a practical roadmap that maximizes your results while minimizing wasted money and effort. The key is thinking strategically—not just about what to buy, but when to buy it and how each piece works with the others.

The Recommended Order

Based on everything we've covered, here's the optimal upgrade sequence for a stock 5.7L HEMI:

1. Cold Air Intake — Easy install, immediate throttle response improvement, great sound enhancement
2. Cat-Back Exhaust — Moderate install, significant power gains, transforms the exhaust note
3. Throttle Body (Optional) — If budget allows, add before tuning to include in calibration
4. Handheld Tuner — Unlocks the full potential of all your hardware upgrades at once

This sequence makes sense for several reasons:

• Each upgrade builds on the previous one, creating a complementary system
• You can enjoy incremental improvements as you go—no need to wait until everything is installed
• Tuning comes last, so you calibrate for your complete package in one shot
• The total investment stays manageable, spread across multiple purchases

Realistic Expectations: What You'll Gain

Let's talk real numbers. A stock 5.7L HEMI puts down approximately 340–360 horsepower at the crank (or roughly 290–310 at the rear wheels, accounting for drivetrain losses). With the full Stage 1–3 bolt-on package, here's what you can realistically expect:

That's a potential 40–70 rear-wheel horsepower from bolt-on modifications alone—a 15–25% improvement over stock. You'll feel it in every pull from a stoplight, every highway merge, and every time you crack the throttle open.

Common Mistakes to Avoid

We've seen a lot of HEMI builds over the years—some great, some not so great. Here are the most common mistakes beginners make:

• Tuning too early: Getting a tune before your hardware is complete means paying for multiple tunes as you add parts
• Skipping the tune entirely: Bolting on parts without tuning leaves 30–40% of your potential gains on the table
• Buying cheap parts: Bargain-bin intakes and eBay exhaust systems often fit poorly, fail prematurely, or underperform. Invest in quality components from reputable brands
• Ignoring maintenance: Performance modifications amplify whatever condition your engine is in. Make sure your 5.7L is healthy before modifying—fresh spark plugs, clean oil, no underlying issues
• Expecting miracles: Bolt-ons are fantastic, but they're not going to turn your 5.7L into a Hellcat. Set realistic expectations and enjoy the meaningful gains you'll actually achieve

What Comes Next?

Once you've completed the basic bolt-on stages, you'll have a solid foundation for more advanced modifications if you choose to continue. Future upgrades to consider include:

• Long-tube headers: The next major exhaust upgrade for serious power gains (15–30+ HP)
• Camshaft upgrade: Changes the engine's personality and powerband—a significant step up in complexity and cost
• Ported intake manifold: Improves airflow into the cylinders for top-end power
• Forced induction: Supercharger or turbo kits for those chasing big power numbers

But here's the important thing: you don't have to go further. A well-executed bolt-on build with a quality tune creates a fantastic driving experience—more power, better sound, sharper response—while maintaining complete reliability and drivability. Many HEMI owners stay at this level for years and love every mile.

Your Build Starts Here

The path from stock to modified doesn't have to be overwhelming. Start with an intake, add an exhaust, finish with a tune, and enjoy the transformation. Each step is an achievable weekend project that brings real, measurable improvements to your 5.7L HEMI.

The most important thing is to start. Pick your first upgrade, order the parts, and get your hands dirty. You'll learn more from one installation than from months of forum reading—and you'll be hooked on making your HEMI faster.

Final Thoughts

Modifying your 5.7L HEMI doesn't require a massive budget or advanced mechanical skills. The three-stage approach outlined in this guide—intake, exhaust, and tuning—represents the most effective way to unlock your engine's hidden potential while maintaining reliability and drivability.

By following the smart upgrade path, you'll:

• Gain 40–70+ rear-wheel horsepower from proven bolt-on modifications
• Transform your HEMI's throttle response and sound character
• Learn valuable skills that prepare you for more advanced builds
• Avoid the common mistakes that waste money and leave power on the table

The 5.7L HEMI is one of the most rewarding engines to modify. It responds eagerly to bolt-on upgrades, and the aftermarket support is exceptional. Whether you're chasing a specific horsepower number or simply want a more engaging driving experience, the mods in this guide will get you there.

Ready to start your build? Browse our complete selection of 5.7L HEMI performance parts and take the first step toward unlocking your HEMI's true potential.