Why Upgrade the Exhaust on Your Datsun 240Z?

The Datsun 240Z, launched in the early 1970s, earned its place as a driver’s car thanks to its lightweight body, independent rear suspension, and a willing 2.4-liter inline-six engine. Forty-plus years later, many owners find that the factory exhaust system—compromised by restrictive bends, small-diameter piping, and aged components—holds back the car’s true potential. Replacing it with a modern aftermarket system like the Greddy (often branded as Trust in Japan) is one of the highest-impact modifications you can make. Not only does it liberate horsepower, but it also sharpens throttle response and transforms the acoustic character of the L-series engine.

Greddy, a household name in Japanese performance tuning, has been producing exhaust systems since the 1980s. Their systems are engineered to improve exhaust scavenging, reduce backpressure, and yield measurable gains across the power band. The Datsun 240Z kit is purpose-built for the chassis, meaning it fits without cutting or major rework. But what does that mean in real-world numbers, and what should you budget? This expanded guide covers performance data, cost breakdowns, installation deep dives, and key considerations to help you decide if a Greddy exhaust is the right upgrade for your Z.

Understanding the Greddy Exhaust System for the 240Z

The Greddy exhaust system for the Datsun 240Z is a cat-back (or full header-back) configuration that replaces everything from the exhaust manifold to the tailpipe. Most Greddy systems are constructed from T304 stainless steel, which resists corrosion far better than mild steel, and feature mandrel-bent tubing to maintain a consistent internal diameter. This ensures that exhaust gases flow freely without turbulence-causing restrictions.

Key components of a typical Greddy system include:

  • Mandrel-bent piping in 2.5-inch or 3-inch diameter (stock is roughly 1.75 inches).
  • High-flow catalytic converter (optional, for street legality).
  • Muffler using a straight-through design with sound-absorbing packing.
  • Stainless steel TIG-welded hangers that match factory mounting points.
  • Polished tip available in various sizes (often 4.5-inch or 5-inch).

Greddy’s engineering philosophy focuses on scavenging—the phenomenon where the velocity of exhaust gases leaving the cylinder helps pull in the next intake charge. By optimizing pipe diameter and muffler internals, the system improves volumetric efficiency without introducing excessive noise. For the 240Z, the result is a net power increase of 8 to 15 horsepower at the wheels, depending on engine condition and supporting modifications.

Performance Gains: Beyond the Butt Dyno

Horsepower and Torque Curves

Factory-restricted exhaust systems rob power because they create backpressure that forces the engine to work harder to expel spent gases. The Greddy system reduces this resistance, allowing the engine to reach peak rpm more freely. On a stock 240Z (150 hp net under JIS standards), expect gains of 10–12 hp at the flywheel and 8–10 lb-ft of torque, with the peak torque arriving slightly earlier in the rev range. Dyno tests from Greddy USA and independent Z-car specialists show consistent improvement from 3,000 rpm to redline, with the highest additive gains near 5,500 rpm.

If your engine already has a mild cam, aftermarket intake, or upgraded ignition, the Greddy system will amplify those benefits. The larger piping supports higher flow rates, so the exhaust no longer becomes a bottleneck. Many owners report that the car “pulls harder” through fourth and fifth gears, and the engine seems more eager to rev on throttle tip-in.

Throttle Response and Engine Efficiency

Beyond peak numbers, the Greddy exhaust improves transient response. The reduced backpressure means the engine can accelerate and decelerate faster without fighting the exhaust system. This is particularly noticeable when blipping the throttle for downshifts or when exiting tight corners. Better scavenging also helps with cylinder filling at low-to-mid rpm, which can improve fuel atomization and, under steady cruising, yield a small fuel economy improvement (typically 1–2 mpg).

Sound and Weight Reduction

The stock 240Z exhaust is quiet and muted. The Greddy system produces a deep, authoritative tone that grows into a refined growl under load. At cruising speeds (2,500–3,000 rpm) it remains civil enough for daily driving, but when the throttle opens, the inline-six sound becomes more dramatic—without the rasp of some cheap aftermarket units. The stainless steel construction is also lighter than the original heavy gauge steel, trimming 10–20 pounds from the rear of the car, which is unsprung mass that improves ride quality and handling.

Cost Considerations: Breaking Down the Investment

System Pricing

The Greddy cat-back exhaust for the Datsun 240Z typically retails between $500 and $1,200. The price depends on whether you choose the standard stainless steel system ($500–$800) or the premium Titanium or “SP” series models ($900–$1,200). Titanium systems are lustrous and even lighter, but they can be harder to source for older Z cars. As of mid-2025, most specialized Z-car parts retailers still stock the Greddy system under its Japanese Trust brand.

Installation Labor

DIY installation is straightforward if you have basic mechanical skills and a jack. Professional installation at a muffler shop or independent Japanese performance shop generally runs $100–$300. The labor covers lifting the car, removing the old system (which may involve cutting rusted bolts), fitting the new system, and aligning the hangers. If you purchase the system new, some online retailers include a discount on installation if you use their partner shops.

Additional Parts and Contingencies

New gaskets (exhaust manifold to downpipe)$10–$25
Stainless steel band clamps (if not included)$10–$20
Replacement hangers (rubber isolators)$15–$40
O2 sensor bung (if adding wideband)$15–$30
Heat wrap or ceramic coating (optional)$50–$150

Total additional expenses: approximately $50 to $300, for a complete installation cost of $600 to $1,500 all-in (parts + labor + incidentals). That’s competitive with other premium exhaust systems from MSA, ZCar Depot, or Borla.

Step-by-Step Installation Guide

Tools and Preparation

Before starting, ensure you have:

  • Floor jack and jack stands (or car lift)
  • Penetrating oil (e.g., WD-40 or PB Blaster)
  • Socket set (10mm, 12mm, 14mm, 17mm)
  • Combination wrenches (same sizes)
  • Pry bar or exhaust hanger removal tool
  • Torque wrench
  • Safety glasses and gloves

Work on a level surface. Allow the exhaust to cool completely if the car was driven.

Removing the Stock Exhaust

  1. Spray penetrating oil on all nuts and bolts (exhaust manifold studs, flange connections, hanger rubber bushings). Let it soak 15–20 minutes.
  2. Raise the car high enough to work under it safely—use jack stands, never the jack alone.
  3. Unbolt the exhaust downpipe from the exhaust manifold. On the 240Z, this requires a 14mm wrench. Be cautious—studs can break; if they do, drill out and replace them.
  4. Loosen the band clamps connecting the downpipe to the center pipe and the center pipe to the muffler section.
  5. Support the exhaust while removing the rubber hangers. A pry bar helps slide the metal hook out of the rubber grommet.
  6. Lower the complete exhaust system. Cut it into pieces if necessary (angle grinder with cut-off wheel) if the bolts are seized.

Installing the Greddy System

  1. Transfer the oxygen sensor (if equipped) from the old exhaust to the new system—Greddy supplies a bung. Use a new crush washer.
  2. Fit the new downpipe (if included) to the manifold with a new gasket. Torque bolts to 30–35 lb-ft.
  3. Attach the center section loosely. Slide the band clamps over the pipe ends, then tighten finger tight.
  4. Mount the muffler section and attach the hangers. Greddy systems use OEM‑style rubber bushings—ensure they seat fully.
  5. Adjust the tailpipe tip position. Leave all clamps slightly loose until alignment is perfect.
  6. Working from front to back, tighten all clamps and flange bolts to 35 lb-ft. Do not over-tighten band clamps—they can distort the pipe.
  7. Lower the car. Re-check hanger clearance—make sure no pipe contacts the chassis, differential, or sway bar.
  8. Start the engine and inspect for leaks. Hold a rag near the tailpipe to feel for pulsations; a hiss indicates a leak at a joint.

Total DIY time: 1.5 to 3 hours. For a first-timer working with rusty hardware, allow 4 hours.

Maintenance and Longevity

Stainless steel Greddy systems are designed to outlast the car itself, but proper care maximizes performance. Avoid using acidic wheel cleaners that contact the exhaust, as they can etch the surface. After washes, drive the car to dry the pipes or use compressed air. Every six months, inspect the hangers for cracking and the flanges for leaks (a carbon trace around a joint indicates a leak). The muffler packing can degrade over 60,000–100,000 miles; if the system sounds quieter or develops rattles, repacking is possible on serviceable mufflers.

If you plan to track the car, consider adding a heat shield for the rear valance—the larger tip and lower muffler position can transfer more heat to the paint or bumper area. Some owners also wrap the downpipe section to reduce underhood temperatures.

Comparing Greddy to Other Exhaust Options

Greddy is not the only player in the 240Z exhaust market. Here’s how it stacks up against alternatives:

  • ZCar Depot / MSA Premium: Similar stainless steel quality, slightly louder, about $100 cheaper. Fitment is good but requires minor sag adjustments on some cars.
  • Borla: More expensive ($1,200+), aggressive sound, lifetime warranty. Heavier than Greddy titanium.
  • Custom exhaust shop: Cheapest option ($300–$500), but variable quality. Likely louder and prone to drone. No resale value.
  • Nissan OEM replicas: Restore original sound but gain zero performance. Priced similarly to Greddy ($600–$800).

Greddy occupies the sweet spot of price, performance, and sound quality. The meticulous Japanese engineering ensures a seamless fit and a refined yet sporty note—qualities that custom shops rarely achieve without trial and error.

Real Owner Experiences

Many Datsun 240Z owners on forums like Classic Z Cars Club and ZCar.com share dyno reports and driving impressions. One common thread: the Greddy system transforms the car without overwhelming it. Drivers report that the power comes on more smoothly, the engine builds revs more quickly, and the sound is “exotic” without being obnoxious. Several owners noted that after installing a Greddy exhaust, they also upgraded the intake and ignition—the system complements other modifications.

“My 240Z was completely stock except for a K&N drop-in. Adding the Greddy cat-back woke the engine up. It pulled past 6,000 rpm like never before—and the sound at full throttle is intoxicating. I did the install in about 2 hours, and it was the best $700 I’ve spent on the car,” writes one forum member.

Another adds: “I had a cheap glasspack system from the ’80s. The Greddy is night and day in terms of drone. The highway is genuinely quiet enough to hold a conversation, yet when you step on it, the car sounds purposeful. Ten out of ten.”

Conclusion: Is the Greddy Exhaust Worth It?

For Datsun 240Z owners seeking to enjoy their car’s performance to the fullest, the Greddy exhaust system represents a well-engineered, cost-effective upgrade. You gain 10–15 horsepower, improved throttle response, a richer sound, and a reduction in weight. The initial investment of $500–$1,200 plus installation is modest compared to other engine modifications (cam, carburetors, internals) that often require complementary exhaust work anyway.

Whether you install it yourself or hire a shop, the Greddy system will make your 240Z more engaging to drive—more powerful, more responsive, and more memorable. It is a proven aftermarket part from a brand that has supported Japanese performance cars for decades. Pair it with a well-tuned SU carburetor setup or a later triple-Weber conversion, and your L-series engine will reward you mile after mile.

If you need additional information or want to purchase a Greddy exhaust system for your Datsun 240Z, check specialized retailers like RockAuto or Greddy Performance Products. Always confirm compatibility with your exact model year (1970–1973) to ensure proper fitment.