Best Exhaust Systems for the Datsun 240z: Achieve 15-20 Hp Gains with Magnaflow or Borla

Introduction: Breathing New Life Into Your Datsun 240Z

The Datsun 240Z (Nissan S30) is a legendary sports car that defined an era. Its light weight, balanced chassis, and high-revving L-series inline-six engine made it an instant classic. But fifty years later, the stock exhaust system—restrictive, heavy, and prone to rust—is a serious bottleneck. Replacing it with a modern performance exhaust is one of the most effective and satisfying upgrades you can make. In this guide we dive deep into the best exhaust systems for the 240Z, focusing on two proven options from MagnaFlow and Borla. Both can deliver real-world gains of 15–20 horsepower along with a dramatic improvement in sound and driving experience.

Why Upgrade Your Exhaust System?

The stock 240Z exhaust was engineered for cost and noise regulations of the early 1970s, not for peak performance. Here’s what you gain by upgrading:

Increased horsepower: a well-designed exhaust reduces backpressure, allowing the engine to expel spent gases more efficiently. This can translate to 15–20 HP at the wheels—a noticeable bump in a car that originally made around 150 HP at the crank.
Improved sound: the L-series six is famous for its smooth, melodic note. A quality aftermarket exhaust unlocks a deeper, more aggressive tone without being obnoxious or drone-heavy.
Better fuel efficiency: improved exhaust flow means the engine doesn’t work as hard to push out gases. Under normal driving, many owners report a small but welcome improvement in gas mileage.
Weight reduction: stock systems often use heavy steel and multiple mufflers. Aftermarket stainless steel systems can shave 10–20 pounds off the rear of the car, helping both acceleration and cornering.
Longevity: modern stainless steel (like T-304) resists corrosion far better than the original mild steel, meaning the system will outlast the car if well-maintained.

Top Exhaust Systems for the Datsun 240Z

While many brands offer 240Z exhausts, MagnaFlow and Borla consistently top the list for build quality, sound, and performance. Let’s examine each in detail.

1. MagnaFlow Exhaust System

MagnaFlow is one of the most popular aftermarket exhaust brands in the world, and their 240Z system is a favorite among enthusiasts who want a deep, muscular tone with minimal drone. The system typically replaces the entire cat-back (or in many cases, the full exhaust from the header to the tip).

Key features:

Stainless steel construction: MagnaFlow uses T-409 or T-304 stainless steel depending on the specific kit. T-304 is the premium choice, offering maximum corrosion resistance and a polished finish that looks great under the car.
Straight-through perforated core mufflers: MagnaFlow’s signature design uses a straight-through tube surrounded by stainless steel wool and a perforated core. This minimizes backpressure while delivering a distinct, aggressive sound.
Aggressive tone with low drone: The muffler tuning is designed to keep interior resonance (drone) at bay during highway cruising while letting the inline-six sing under throttle.
Complete bolt-on fitment: Most systems are designed to bolt directly to the stock headers or downpipe using the original hangers. Some models require minor modifications to the tailpipe mounting, but overall installation is straightforward.
Lifetime warranty: MagnaFlow backs their exhausts with a limited lifetime warranty against defects and corrosion (as long as you own the vehicle).

Typical setup for 240Z: A common MagnaFlow kit includes a 2.5-inch diameter main pipe (up from the stock 1.75–2.0 inch), a single high-flow muffler, and a polished stainless steel tip. Some variations add a resonator for even quieter cruising.

Sound profile: Deep and throaty at idle, with a smooth growl through the mid-range. At full throttle the L-series takes on a classic straight-six howl that sounds fantastic without being offensive to neighbors.

For official specs and fitment details, visit the MagnaFlow official website and search for Datsun 240Z applications.

2. Borla Exhaust System

Borla is another powerhouse in the performance exhaust world, known for their highly engineered multi-core mufflers and distinctive, race-bred sound. The Borla system for the 240Z is often considered the premium option, with a more aggressive bark and motorsport heritage.

Key features:

T-304 stainless steel throughout: Borla uses only T-304, the highest grade of stainless steel, on their aftermarket exhausts. It’s stronger, more rust-resistant, and easier to polish than T-409.
Multi-core muffler technology: Instead of a single straight-through pipe, Borla uses a series of perforated tubes and chambers (their patented “Aero-Turbine” or “XS” mufflers) that cancel out unpleasant frequencies while amplifying the engine’s natural sound.
Distinctive exhaust note: A Borla exhaust is immediately recognizable—it has a sharper, more aggressive bark than a MagnaFlow, with a pronounced crackle on deceleration.
Lifetime warranty: Borla offers one of the best warranties in the industry: 1 million miles or the life of the vehicle (transferable to subsequent owners). Service centers nationwide honor it.
Mandrel-bent tubing: All Borla systems use mandrel bends, meaning the inside diameter doesn’t shrink at curved sections. This maximizes flow and horsepower.

Typical setup for 240Z: Borla’s kit generally includes a 2.5-inch mandrel-bent system with a single large muffler (some versions use two small ones for a dual-exit look). The tip is a large, polished, rolled-cut design that fills the rear valance opening perfectly.

Sound profile: Louder and more aggressive than MagnaFlow. Ideal for drivers who want the car to sound like it’s ready for the track. Some owners report noticeable interior drone at certain RPMs in the 2500–3000 range, so it’s worth considering if you do a lot of highway driving.

Check Borla’s official product page for current Datsun 240Z listings and dyno charts.

Performance Gains: Real-World Dyno Results

Both MagnaFlow and Borla systems are proven to deliver significant gains on the L24 and L28 engines. Typical dyno runs show:

Peak horsepower increase: 12–18 HP at the wheels on a well-tuned engine (15–20 HP at the crank). The gain is most pronounced in the mid-range (3500–5500 RPM) where the stock exhaust chokes the engine.
Torque improvement: 10–15 lb-ft gains across the powerband, with a noticeable flattening of the torque curve. The car feels more responsive from 2000 RPM onward.
Throttle response: Cleaner exhaust scavenging improves throttle tip-in, especially when combined with a header upgrade like the MSA (Motorsport Auto) 6-into-1 or 6-into-2 systems.
Comparison: On a typical L28 with mild cam and SU carbs, a MagnaFlow system might produce slightly more mid-range torque (due to its straight-through design), while a Borla might peak slightly higher in HP near redline due to its more aggressive muffler tuning. In real-world driving, both feel strong.

To maximize gains, pair the exhaust with a header upgrade, a free-flowing air filter (like a K&N), and a professional tune of the carburetors (or EFI system). Some owners also replace the stock downpipe with a larger unit to eliminate another restriction. With all three upgrades, 20–30 HP gains are possible.

For independent dyno tests, see Motorsport Auto’s tech library and online forums like Classic Z Cars Club.

Installation Tips for a Smooth Fit

Replacing a 240Z exhaust is a manageable DIY job for anyone with basic tools and a weekend. Here’s a step-by-step guide to get the best results.

What You’ll Need

Floor jack and jack stands (or ramps)
Set of metric wrenches and sockets (10mm, 12mm, 14mm, 17mm)
Penetrating oil (WD-40 or Kroil)
Wire brush or grinder with flapper disc for rusty bolts
Rubber mallet (for stubborn hangers)
Safety glasses and gloves
Optional: an exhaust hanger removal tool or pry bar

Preparation

Let the car cool completely. Exhaust components get very hot and can cause burns.
Spray all bolts and hangers with penetrating oil 24 hours before starting. The 240Z’s underbody is prone to rust, especially in the Northeast or Midwest.
Raise the car securely on stands. You need enough clearance to slide the old system out from under the car.

Removing the Old System

If your car still has the original bolts, they may be seized. Use a breaker bar or impact wrench. If a bolt snaps, drill it out or use a bolt extractor.
Remove the muffler hangers. Original rubber hangers can be rock-hard; cut them off with a utility knife and replace with new universal hangers.
Lower the entire exhaust assembly carefully. It’s heavy and will have sharp edges. Get a helper if possible.

Installing the New System

Test-fit the new system before tightening anything. Start at the header/downpipe connection and work your way back, aligning hangers and making sure the tailpipe fits properly in the rear valance cutout.
Use new gaskets at the manifold-to-downpipe joint and any other flanges. Most aftermarket systems come with them, but buy extras if not.
Tighten gradually. Start from the front and go back, snugging each clamp. Final torque: hand-tight plus a quarter-turn with a wrench. Over-tightening can crush the pipe or distort flanges.
Check clearance. Make sure the exhaust doesn’t touch the transmission mount, crossmember, or differential. Leave at least ½ inch of clearance from body panels to prevent rattles.
After tightening, start the engine and listen for leaks. Use a roll of mechanic’s wire or a shop cloth to temporarily plug the tailpipe—if you hear a hiss under the car, you have a leak. Tighten clamps or apply exhaust sealant if needed.

Final Checks

Let the car run for 10 minutes, then check for smoke or burning smells. Some new exhausts have protective oils that burn off in the first 20 minutes.
Take a short drive and listen for drone at highway speeds. If it’s too loud, you can add a resonator or swap to a quieter muffler.

Pro tip: Replace the exhaust hangers with modern polyurethane versions. They last years longer than rubber and reduce vibration transfer to the chassis.

Sound Comparison: MagnaFlow vs. Borla

Sound is subjective, but there are clear differences. Here’s how they stack up:

MagnaFlow: Deep, smooth, and refined at idle. Under acceleration it builds to a clean howl, but never becomes harsh. Minimal interior drone below 3000 RPM. Best for daily drivers who want a sporty note without fatiguing passengers.
Borla: Louder, sharper, and more aggressive throughout. A pronounced snap on throttle blip and a crackle on deceleration. A bit more drone in the 2500–3000 range. Best for enthusiasts who track their car or want the car to announce its presence.

If you want a comparative sound clip, search YouTube for “Datsun 240Z MagnaFlow vs Borla” – there are several high-quality videos from owners.

Material and Build Quality

Both brands use high-quality stainless steel, but there are differences:

Feature	MagnaFlow	Borla
Steel grade	T-409 (main pipes) / T-304 (some kits)	All T-304
Muffler design	Straight-through perforated core	Multi-core (chambered with tubes)
Welding	Robotic TIG/MIG, consistent	Hand TIG-welded, beautiful work
Warranty	Lifetime (limited, non-transferable)	1 million miles (transferable)
Tip finish	Polished or brushed	Mirror-polished

For daily use in salt-free climates, T-409 is perfectly adequate. If you live in the Rust Belt or drive in winter, Borla’s all-T-304 construction might provide an extra margin of durability. Both brands’ welds are excellent, but Borla’s hand-finishing is notably more artistic.

Tuning Considerations for Maximum Gains

An exhaust upgrade is just one piece of the puzzle. To truly reap the 15–20 HP gain, your engine needs to be in good shape and properly tuned. Key points:

Headers: The stock exhaust manifold is a cast iron piece with restrictive ports. Replacing it with a 6-into-1 header (e.g., MSA, Stahl) will drastically improve flow and let the exhaust system do its work. Combined gains of 25–35 HP are common.
Carburetion or EFI: The L-series typically uses SU or Weber carburetors. If the mixture is too lean or too rich, you won’t see the full benefit. Re-jetting carbs after an exhaust upgrade is highly recommended. For EFI swaps (e.g., Megasquirt), a dyno tune is essential.
Ignition timing: More efficient exhaust changes the engine’s volumetric efficiency. Advancing timing slightly (to 12–14 degrees initial) often yields more power. Avoid detonation by checking with wideband O2 sensor.
Camshaft: A mild performance cam (like a Stage 1 from Isky or MSA) will make the exhaust system even more effective. But even a stock cammed engine sees nice gains.

Word of caution: Don’t expect 20 HP from just a cat-back system on an otherwise stock, tired engine. If your rings are worn or your valves are leaking, fix those issues first. A good baseline compression test is a sound investment.

Cost and Value

Prices vary by vendor and configuration, but expect to pay:

MagnaFlow system: $350–$550 (depending on whether full cat-back or axle-back, and tip style). Excellent value for the quality.
Borla system: $500–$750. The premium is justified by the T-304 stainless steel, transferable warranty, and more aggressive sound tuning.
Installation: $200–$400 if you have a shop do it. Most enthusiasts do it themselves, saving that cost.

Consider the long-term value: Borla’s million-mile warranty is essentially a lifetime guarantee. If you ever sell the car, a Borla system is a strong selling point. MagnaFlow is a fantastic choice for a more budget-conscious build.

Conclusion: Which System Should You Choose?

Both MagnaFlow and Borla exhaust systems for the Datsun 240Z deliver the promised 15–20 HP gains, better sound, and reduced weight. Your choice depends on your priorities:

Choose MagnaFlow if: you want a deep, smooth tone, minimal drone, and a great price-to-performance ratio. It’s the ideal daily-driver upgrade.
Choose Borla if: you want the loudest, most aggressive L-six sound, premium T-304 stainless steel, and a transferable warranty. It’s the choice for enthusiasts who track or show their car.

No matter which you pick, upgrading the exhaust is one of the most satisfying modifications you can make to a 240Z. The combination of more power, a wonderful sound, and the knowledge that you’ve unlocked your car’s potential makes every drive a thrill. Pair it with a fresh tune and perhaps a set of headers, and you’ll have a classic sports car that can hold its own on modern roads.

For further reading, check out the official product pages linked above, and join the community at ZCar.com for owner reviews and installation guides.