Mercedes-AMG X290 GT63 S M177.2 Modder's Guide
Produced from 2019 to 2023, the Mercedes-AMG GT63 and GT63 S (X290) are powered by the hand-built 4.0L twin-turbo M177 LS2 V8 paired with AMG's 9-speed MCT transmission and AMG Performance 4MATIC+. Sharing much of their drivetrain with the W213 E63 S, both models respond extremely well to tuning. With an ECU/TCU tune and basic bolt-on modifications, the M177.2 can gain well over 200 crank horsepower while maintaining excellent drivability.
GT63 vs. GT63 S & Pre-Facelift vs. Facelift Differences
GT63 S Pre-Facelift
GT63 S Post-Facelift
The GT63 S receives factory upgrades including higher-output ECU tuning (630 HP vs. 577 HP), an electronically controlled limited-slip rear differential, stiffer suspension, Race driving mode, dynamic engine mounts, and the option to add carbon ceramic brakes. The GT63 shares the same core M177.2 engine and transmission, making both cars nearly identical once modified. For most enthusiasts, the GT63 represents the better value, while the GT63 S offers additional factory performance features mostly pertaining to suspension hardware.
GT63 Aftermarket Platform (Stages)
Note: We recommend pairing any ECU tune with a TCU tune to maximize power delivery, shift quality, and reliability.
GT63 Stage 1
Consists of an ECU tune on premium pump fuel, often paired cold air intakes or drop in air filers. A TCU tune further improves shift quality and torque management. Expect approximately 680-750 crank horsepower, depending on fuel quality and calibration, with 60-130 mph times generally falling into the low- to high-seven-second range. Fresh spark plugs, ignition coils, and routine maintenance are recommended before tuning.
GT63 Stage 2
Adds catless or high-flow downpipes alongside ECU and TCU tuning. This is the sweet spot for most GT63 owners, producing approximately 750-850 crank horsepower with 60-130 mph times commonly falling into the high five to mid-six-second range depending on fuel, tires, and tune.
GT63 Stage 2+
Introduces ethanol blends such as E30 with proper calibration and fuel system monitoring. Expect approximately 850-900+ crank horsepower and low- to mid-five-second 60-130 mph times.
GT63 Stage 3
Combines upgraded or hybrid turbochargers (we recommend PTG) with downpipes, custom tuning, and supporting high pressure (PTG) and low pressure fuel pumps (Spool). Well-built setups can approach or exceed 1,000 crank horsepower, with 60-130 mph times in the mid-four to low-five-second range.
If you are interested in custom tuning, we recommend experienced Mercedes-AMG specialists such as A1 Automotive, MPE California, and Eurocharged. Please reach out to us via email at contact@gappedindustries.com or Instagram @gappedindustries if you're interested in tuning your Mercedes-AMG.
GT63 Exterior Modifications
Carbon fiber front lips, rear diffusers, trunk spoilers, side skirts, mirror caps, and other exterior trim help give the GT63 a lower, wider, and more aggressive appearance while offering modest aerodynamic benefits. Forged wheels and high-performance tires also improve handling by reducing unsprung weight and increasing grip. For most owners, subtle OEM+ carbon fiber provides the cleanest overall appearance.
GT63 Suspension and Handling
The GT63 uses AMG Ride Control+ adaptive air suspension, which performs exceptionally well from the factory. Lowering modules, lowering links, or suspension coding are the most common upgrades. We recommend lowering the vehicle approximately 1-1.5 inches while maintaining proper alignment to maximize appearance, handling, and tire life. As with any lowered air suspension vehicle, expect somewhat increased inner tire wear.
Our Recommendations for the GT63
For owners seeking a stock or OEM+ build, we recommend subtle carbon fiber exterior components, forged wheels, quality tires, a mild lowering setup, and preventative maintenance.
For the ideal street build, Stage 2 with catless downpipes, ECU/TCU tuning, fresh spark plugs, carbon fiber aero, upgraded wheels, and high-performance tires provides the best balance of performance, drivability, and value.
For enthusiasts chasing maximum performance, Stage 3 or Stage 3+ with upgraded turbochargers, upgraded fueling, ethanol tuning, cooling upgrades, and careful drivetrain calibration unlocks the full potential of the M177 LS2 platform.
Whether your goal is a refined grand tourer or a 1,000+ horsepower street car, the X290 GT63 remains one of Mercedes-AMG's most capable modern platforms.
Frequently Asked Questions (FAQ)
What maintenance should I do before tuning my GT63?
Before tuning your GT63, ensure the car is up to date on maintenance, including fresh engine oil, properly gapped spark plugs, healthy ignition coils, and clean air filters. We also recommend checking all fluids, inspecting for leaks, and scanning for fault codes before installing an ECU tune.
Is the GT63 Reliable?
Yes. The M177.2 is one of Mercedes-AMG's most reliable modern V8s when properly maintained. We recommend oil changes every 3,000-5,000 miles, regular service roughly three times per year, and monitoring common wear items such as the rear main seal, especially on tuned vehicles.
How Much Ethanol Can a GT63 Run Safely?
We generally recommend E25 as a conservative limit on the factory fuel system. Higher ethanol blends should only be used with proper tuning and supporting fuel system upgrades, like PTG's HPFP.