Upgrading to a Borla cat-back exhaust system on your Infiniti G37 is one of the most rewarding modifications you can make. Not only does it unlock a deeper, more aggressive exhaust note, but it also delivers measurable performance gains. However, separating marketing claims from real-world results is essential before you invest. This article provides a thorough, data-driven breakdown of exactly how much horsepower a Borla cat-back exhaust adds to a G37, what influences those numbers, and why this particular brand has earned such a loyal following among VQ37VHR enthusiasts.

What Is a Cat-Back Exhaust System and Why It Matters

A cat-back exhaust system replaces everything from the catalytic converters rearward — typically including the Y-pipe, mid-pipe, resonator, mufflers, and tailpipes. The stock G37 exhaust is designed for quiet operation and cost efficiency, with multiple pinch points and restrictive mufflers that create backpressure. While some backpressure is necessary for scavenging at low RPM, the factory system leaves significant airflow potential on the table. By reducing restriction, a cat-back system allows the engine to expel exhaust gases more freely, which in turn reduces pumping losses and can increase volumetric efficiency. This translates to modest but genuine horsepower and torque gains across the rev range, along with improved throttle response.

Why Borla Stands Out for the G37

Borla has been a leading name in performance exhausts since the 1970s, and their offerings for the Infiniti G37 are engineered with aerospace-grade materials and proprietary technology. Key differentiators include:

  • T-304 Stainless Steel Construction: Borla uses only high-nickel-content stainless steel, which resists corrosion and cracking far better than the aluminized steel used in many budget exhausts.
  • Patented Multi-Core Technology: Borla mufflers utilize non-woven, sound-absorbing material wrapped around progressive core tubes. This design delivers a refined, drone-free interior while still providing an aggressive exterior tone.
  • Million-Mile Warranty: Borla backs their exhausts with a limited lifetime warranty that is transferable, reflecting confidence in their build quality.
  • Tailored Sound Profiles: Borla offers three distinct exhaust series for the G37 — S-Type, ATAK, and Touring — allowing owners to choose their preferred combination of volume and tonality.

For G37 owners who prioritize a premium fit and finish, Borla is a top-tier choice that avoids common issues like drone, rasp, or premature rusting.

Detailed Horsepower Gains from Borla Cat-Back on the G37

The horsepower gain from a Borla cat-back exhaust on a G37 depends heavily on which specific model you install, whether you pair it with other modifications, and how well your engine is running. On a completely stock G37 with no other bolt-ons, the increase at the wheels is typically between 5 and 12 horsepower, with a more noticeable gain in the 4,500–7,000 RPM range. To understand these numbers better, let's examine each Borla series individually.

The Borla S-Type is engineered for a balanced approach — more aggressive than the Touring but not as extreme as the ATAK. It features a single large core resonator and dual large core mufflers. On a stock G37, the S-Type generally produces 8–10 wheel horsepower and 7–9 lb-ft of torque at peak gains, with a broad improvement of about 5–7 WHP throughout the midrange. Owner dyno plots from forums like MyG37 and G37Driver consistently show these figures, with the torque curve flattening and lifting slightly after 4,500 RPM.

Borla ATAK (Maximum Aggression)

The ATAK (pronounced "attack") is Borla's loudest and most performance-oriented system. It uses larger core mufflers and less sound deadening to maximize flow and volume. On a stock G37, the ATAK can show peak gains of 10–15 wheel horsepower when the car is fresh and properly tuned. However, because the ATAK is louder, some of that perceived gain is subjective — the sound alone makes the car feel quicker. Dyno comparisons between S-Type and ATAK on the same car often show the ATAK pulling ahead by 2–4 horsepower above 6,000 RPM.

Borla Touring (Mild Enhancement)

The Touring series is designed for the enthusiast who wants improved flow and a richer tone without excessive volume. It uses fully polished or carbon fiber tips and additional sound absorption. Expected gains are 5–8 wheel horsepower on a stock G37. The Touring sacrifices a few peak horsepower compared to the S-Type or ATAK but provides a more mature, street-friendly exhaust note that eliminates drone almost entirely.

Real-World Dyno Results and References

Several independent tests provide concrete data. For example, a 2010 G37 Sedan with an automatic transmission and 60,000 miles saw a gain of 11.3 peak WHP and 8.5 lb-ft of torque after installing a Borla S-Type, according to a detailed thread on MyG37.com. Another user on G37Driver posted a dyno sheet from a 2011 G37 Coupe with the ATAK, showing a gain of 14.6 WHP at the peak, with a broad increase from 4,000 RPM onward. While these are sample points, they align with the general experience of the community.

Factors Affecting Horsepower Gains

Not every G37 will respond identically to the same Borla exhaust. Several variables influence the final numbers you'll see on a dyno or feel behind the wheel.

Supporting Modifications

A cat-back exhaust alone is a mild bolt-on. Pairing it with a cold air intake (such as Stillen or Z1) and a tune (e.g., ECUTek or UpRev) can unzip significant additional power. On a G37 with a CAI, tune, and a Borla S-Type, many owners see 15–20 WHP total over stock. Adding long-tube headers can push that figure even higher, though headers come with their own installation challenges and legal considerations.

Vehicle Condition and Maintenance

A well-maintained G37 with clean fuel injectors, fresh spark plugs, and no vacuum leaks will respond better to exhaust flow improvements. If the engine is carboned up or has failing sensors, the ECU may pull timing, limiting the gain. Always ensure your car is in top mechanical shape before chasing performance numbers.

Exhaust Break-In Period

Borla exhausts, like most aftermarket systems, require a break-in period of 200–500 miles. During this time, the fiber packing in the mufflers settles and the metal expands and contracts. Initial dyno runs immediately after installation may show slightly lower numbers; after break-in, the gains often increase by 1–2 horsepower as the system stabilizes.

Installation Process and Considerations

Installing a Borla cat-back on a G37 is a straightforward job for a home mechanic with basic tools, but proper preparation ensures a leak-free fit and long-term satisfaction.

Tools and Time Required

  • Floor jack and jack stands (or a lift)
  • 14mm, 17mm, and 19mm sockets and wrenches
  • Penetrating oil (e.g., WD-40 or PB Blaster)
  • Flathead screwdriver (for removing rubber hangers)
  • Torque wrench (25–35 ft-lb for exhaust clamps)
  • Estimated time: 2–4 hours for an experienced DIYer, 1–2 hours on a lift

Step-by-Step Overview

Start by applying penetrating oil to all exhaust bolts and rubber hanger insulators. Remove the OEM exhaust in sections — typically the mid-pipe and Y-pipe come out as one unit after unbolting from the catalytic converters. The rear muffler section is removed by prying the rubber hangers off. Install the Borla system from front to back: attach the mid-pipe and Y-pipe assembly to the catalytic converters using the supplied gaskets and clamps, then mount the rear muffler section. Adjust the tip alignment before fully tightening all clamps. Run the engine to check for leaks and ensure no rattling against the underbody. More detailed instructions are available in the Borla installation guides.

Professional vs. DIY

If you have access to a lift and are comfortable working with rusted fasteners, DIY installation saves on labor costs (typically $150–$300 at a shop). However, shops can also weld additional bungs for an oxygen sensor or handle stubborn bolts with an acetylene torch. Borla's million-mile warranty is not voided by self-installation, making this a safe project for the experienced home mechanic.

Sound and Driving Experience

While horsepower figures are important, the auditory and tactile transformation is where a Borla exhaust truly shines. The stock G37 exhaust is subdued — even with the factory sport exhaust, tones are muted. A Borla system reveals the VQ37VHR's naturally raspy upper-RPM character while adding a deep, refined growl at low speeds.

In-Cabin vs. Exterior Noise

All Borla systems for the G37 are engineered to minimize drone at highway cruising speeds (around 70–80 mph). The S-Type and Touring are especially quiet inside the cabin during steady throttle, with the exhaust note building predictably as you press the accelerator. The ATAK is louder at all loads and may drone slightly if you are sensitive to it. Outside the car, the sound is purposeful and aggressive without being obnoxious, provided you avoid straight-pipe configurations.

Comparison to Stock

Many owners report that the Borla system makes the G37 feel "freer" and more responsive, especially when passing on the highway or climbing steep grades. The throttle becomes more immediate, and the engine revs more eagerly to redline. This subjective improvement often outweighs the modest dyno numbers — the car simply drives better.

Is a Borla Cat-Back Worth the Investment?

With prices ranging from $1,100 to $1,500 for the full system, a Borla cat-back is a significant investment for a 5–15 wheel horsepower gain. However, the value extends beyond the dyno sheet. The sound quality, build materials, and lifetime warranty make it a long-term addition that holds its resale value. Many owners sell their Borla exhausts used for 60–75% of the original price, indicating strong demand. When combined with other bolt-ons, the power ceiling rises substantially, making it a foundational upgrade for a naturally aspirated or even supercharged G37 build.

If your goal is the most economical horsepower per dollar, a tune alone might yield better gains. But if you want an exhaust that enhances the entire driving character of your G37 — sound, throttle response, and durability — Borla remains one of the best options on the market. For additional perspectives, check out the Borla product page for the G37 S-Type and browse owner reviews on enthusiast forums for real-world feedback.

Conclusion

Upgrading to a Borla cat-back exhaust on your G37 delivers a genuine, repeatable horsepower gain of 5–15 WHP, with the ATAK series providing the top end of that range and the Touring offering a more subtle improvement. The real value, however, lies in the enhanced driving experience — a richer sound, improved throttle response, and peace of mind from a high-quality stainless steel system backed by a transferable warranty. Whether you choose the S-Type, ATAK, or Touring, a Borla exhaust transforms the personality of your G37 without compromising reliability. For the enthusiast seeking a well-rounded performance upgrade, this is one of the smartest investments you can make.