The Case for Twin Scroll Turbocharging

For decades, the Ford Mustang has been a canvas for performance enthusiasts. From street-driven GTs to track-prepped Cobra Jets, the aftermarket has never been short of ways to extract more power. In recent years, turbocharging has surged in popularity, offering a different power delivery curve compared to traditional superchargers. Among turbocharger designs, the twin scroll arrangement stands out for its ability to combine quick spool characteristics with high top-end flow.

Twin scroll turbochargers separate the exhaust pulses from the engine’s cylinders into two distinct channels within the turbine housing. By keeping the exhaust pulses organized — typically grouping cylinders 1-4-6-7 vs 2-3-5-8 on a V8 — the turbo can make better use of the pressure wave energy. This reduces reversion, shortens spool time, and improves volumetric efficiency. For a Mustang owner looking to gain both low-end response and peak power without excessive lag, a twin scroll turbo kit is a compelling choice.

Why Nashville Performance’s Kits Stand Out

Nashville Performance has built a reputation in the high-performance community for designing forced induction kits that prioritize reliability and real-world drivability. Their twin scroll offerings for the Ford Mustang are no exception. Each kit is engineered with a focus on precision fitment, thermal management, and ease of service. The company uses high-grade cast stainless steel for the twin scroll manifolds, Tial wastegates, and Garrett or BorgWarner core turbos — components trusted in competitive racing environments.

One key differentiator is the R&D that goes into each stage. Nashville Performance tunes each kit on a chassis dynamometer, mapping out safe air-fuel ratios and ignition timing curves for pump gas, E85, and even race fuel blends. This means the end user receives a proven calibration, not just a box of parts. The kits also include necessary fuel system upgrades, such as larger fuel injectors and a higher-flowing fuel pump, ensuring the engine can support the additional airflow.

Detailed Breakdown of the Top Kits

NP-Stage1 Twin Scroll Kit: The Daily Driver’s Choice

Designed for Mustang owners who want a significant power bump without sacrificing civility, the NP-Stage1 kit is the entry point into twin scroll performance. It pairs a small-frame twin scroll turbo with a divided T4 flange, allowing quick spool from around 2,800 RPM. The kit includes a front-mount intercooler with cast end tanks, a blow-off valve, and all necessary plumbing in 304 stainless steel or aluminum.

Power output on a stock long-block Coyote or Gen2 5.0L typically lands between 550 and 620 rear-wheel horsepower on 93 octane pump gas. With the included injectors and fuel pump, the kit supports up to 700 RWHP on E85 with an upgraded boost controller. The NP-Stage1 retains factory driveability features such as cold start, idle control, and cruise fuel trims, making it suitable for a daily commute.

Installation is straightforward, with detailed instructions and pre-assembled sub-sections. Most DIYers with moderate mechanical experience can complete the install in a weekend. The kit uses bolt-on connections where possible, avoiding the need for welding or custom fabrication.

NP-Stage2 High-Performance Kit: For the Power Addict

When the first stage isn’t enough, the NP-Stage2 kit steps up with a larger twin scroll turbo, upgraded intercooler core, and a more aggressive camshaft profile. This kit targets the owner who wants to run at the drag strip or road course every weekend. The turbo features a 64mm or 67mm inducer, depending on displacement and fuel choice, and a divided T6 housing that can support up to 1,000 RWHP with proper tuning and E85.

The Stage2 kit adds a custom cold air intake, a three-inch downpipe with a catalytic converter delete option, and a methanol injection provision. The intercooler is 50% larger than the Stage1 unit, capable of sustaining back-to-back pull sessions without heat soak. Included are billet fuel rails and larger injectors (up to 1,300 cc/min). Nashville Performance recommends upgrading to a built short block and selecting a turbo that matches the owner’s power goals and fuel system.

Boost threshold moves slightly higher, around 3,200-3,500 RPM, but once on boost the torque curve is aggressive and sustained well past 7,000 RPM. A dedicated boost controller, included, allows the driver to adjust between low-boost street maps and high-boost race maps.

NP-Stage3 Race-Ready Kit: The No-Compromise Solution

Built for competition use only, the NP-Stage3 kit is for the most hardcore Mustang builds. It assumes the engine has been fully forged and sleeved, and that the transmission and driveline can handle extreme torque. The turbo itself is a billet wheel, ball-bearing unit with a 68mm or 72mm inducer, paired with a massive air-to-water intercooler for near-instant temperature control. Everything from the wastegates (dual Tial 44mm) to the dump tubes and heat shielding is competition-grade.

This kit requires professional installation and tuning, although Nashville Performance offers a turnkey service through its network of certified shops. The power output can exceed 1,500 RWHP on race gas or custom E85 blends. The engine management system is fully programmable, with provisions for stand-alone engine control if the owner wishes to bypass the factory PCM.

The Stage3 kit includes a billet oil pump, a larger scavenge pump for the turbo drain, and a high-amp fuel system with dual pumps. The entire kit is designed for ease of maintenance between rounds, with quick-disconnect couplers for the intercooler lines and a lift-off-style downpipe.

Benefits of Upgrading to a Twin Scroll Turbo Kit

Understanding the practical advantages helps justify the investment. Here are the primary benefits broken down:

Reduced Turbo Lag

Twin scroll designs are famous for their spool characteristics. By preserving exhaust pulse energy, the turbine responds faster to throttle inputs. On a 5.0L Mustang, this can mean reaching full boost 500-800 RPM sooner than a comparable single scroll unit. This transformed the driving experience from “wait for it” to immediate thrust.

Higher Volumetric Efficiency

Because there is less exhaust reversion in the manifold, the engine can scavenge the cylinders more effectively. This increases the effective compression ratio and helps with off-boost power and throttle response. Many owners report that their car feels stronger at partial throttle even before the turbo spools.

Improved Exhaust Gas Scavenging

The separated pulses create a stronger vacuum in the collector, pulling spent exhaust from the cylinders more completely. This reduces pumping losses, which can slightly improve fuel economy under light load. While the primary goal is power, this side benefit is welcome for a street car.

Thermal Efficiency

Twin scroll turbines are more efficient at converting exhaust energy into shaft work. This means less heat is dumped into the engine bay, and the turbo itself runs cooler. The result is lower intake air temperatures and reduced risk of knock, especially when running high boost on pump gas.

Consistency Under Load

Because the exhaust pulses are not interfering with each other, the boost curve is smoother and more predictable. This makes the car easier to drive at the limit, whether on a road course or during a drag launch. The driver doesn’t have to compensate for a sudden wall of boost or a laggy transition.

Installation and Tuning Considerations

Installing a twin scroll turbo kit is not a casual weekend job for a novice, but Nashville Performance has designed their kits to be as DIY-friendly as possible. Still, several factors determine success:

Supporting Modifications

Beyond the kit itself, the engine and drivetrain must be prepared. For the NP-Stage1, a stock Mustang GT with good maintenance can handle 550-620 WHP on pump gas. For Stage2 and Stage3, upgrades to the bottom end, valve springs, and fuel system are mandatory. Nashville Performance provides a comprehensive checklist with each kit, including recommended clutch packs, axles, and differential upgrades.

Professional Tuning

Even though the NP-Stage1 includes a base calibration, it is highly recommended to perform a dynamic tune on a chassis dyno after installation. Fuel quality, altitude, and differences in engine wear all affect the optimal tune. Many shops charge $500-$1,000 for a full session, which is money well spent for reliability.

For those who prefer an off-the-shelf tune, Nashville Performance offers a remote tuning option via HP Tuners. The customer data-logs a few runs and sends the files to the company’s calibration team. This service is included with the purchase of any complete kit.

Intercooler and Heat Management

Twin scroll turbos generate heat. The NP kits include high-efficiency intercoolers and heat shields, but owners should consider adding a larger radiator and oil cooler if the car will see track time. Nashville Performance sells a “cooling upgrade package” that bundles a high-flow water pump, a 170-degree thermostat, and a duct kit for the intercooler.

Comparing Twin Scroll to Other Turbo Configurations

Understanding the alternatives helps clarify why twin scroll is favored for the Mustang. Single scroll turbochargers are simpler and cheaper, but they generally suffer from more lag and a narrower power band. Twin turbo setups — one turbo per bank of cylinders — can offer fast spool, but they add complexity, weight, and cost. They also require twin wastegates, twin intakes, and often more complicated oil drain routes.

Procharger superchargers are a common alternative, but they produce linear power and lack the torque multiplication of a properly sized turbo. Roots-style superchargers provide instant torque but are limited in top-end power and generate more heat. The twin scroll turbo strikes a balance: near-instantaneous boost with strong top-end pull, all while keeping engine bay temperatures lower than a supercharger’s intercooler setup.

For a street-driven Mustang that sees occasional track use, the twin scroll is arguably the best combination of drivability, power, and efficiency. The ability to use smaller turbine wheels without sacrificing top-end flow is the key.

Real-World Results and Community Feedback

Nashville Performance’s twin scroll kits have been installed on hundreds of Mustangs from 2011 to the present day. On forums such as Mustang6G and SVTPerformance, owners report highly satisfied experiences. Many note that the NP-Stage1 kit retains the factory air conditioning and power steering, with no need to relocate the battery or modify the firewall. The Stage2 and Stage3 kits are praised for their robust hardware and clear instructions.

A common comment is that the car becomes “lazy no more” — the low-end torque transforms the driving feel, making the Mustang feel lighter and more nimble. Owners who have previously owned supercharged Mustangs often remark that the turbo car is easier to control in wet conditions because the torque is not immediate; it builds smoothly.

On the track, the twin scroll kit’s ability to maintain boost at high RPM is a clear advantage over centri-style superchargers, which tend to drop off at the top of the rev range. Several road racers have reported winning local championships with NP-Stage2 equipped vehicles.

External Resources for Further Research

Final Thoughts: Choosing the Right Stage for Your Mustang

Before selecting a twin scroll turbo kit, be honest about your driving habits and power goals. If the car is a daily driver that sees the occasional open road or autocross, the NP-Stage1 kit delivers a thrilling increase without breaking the bank or requiring constant upkeep. If you have a track-focused machine and a built engine, the NP-Stage2 or Stage3 kits provide the headroom to dominate at any power level.

Investing in a twin scroll turbo kit from Nashville Performance is a step toward a more responsive, more powerful, and ultimately more enjoyable Mustang. The company’s attention to design, quality components, and proven calibrations means you are not just buying parts — you are buying a fully engineered solution. With proper installation and tuning, your Mustang will reward you with a driving experience few other modifications can match.