McLaren GT ECU Tune M840T

Purchase McLaren GT ECU Tune

SKU: 05-840-00154-7
McLaren GT ECU Tune
Power gain Up To
+133 HP

Torque gain Up To
+85 TQ

Advertised gains are estimates of HP and Torque “at the engine” calculated from gains as measured on a Dynojet Dynamometer in ideal conditions and typically show the largest possible change. Actual gains are dependent on the following: Learn More about Crank HP Vs Wheel HP

Model – Manufacturers use the same engine in multiple model vehicles and often times they are in a different state of tune, for example: 2008 C63 and a 2008 CLK Black Series. Both have the same engine, but the C63 has 451hp while the CLK63 has 500hp. Naturally the C63 will show more gains as it starts at a lower level.

Model Year – Similar to above, as time progresses, Manufacturers tend to slightly increase power output via software from one year to the next or offer “Performance Packages” with increased power. The engines remain largely unaltered and as a result, final tuned output remains the same, while the gains are lower as the starting point is now higher.

Fuel – Fuel quality is HIGHLY important with performance vehicles. Low quality and/or low octane fuel will greatly impact engine output and potentially even engine health. Top tier brand premium fuels should always be used to achieve the best results possible.

Drivetrain – All wheel drive has higher drivetrain losses than rear wheel drive. This results in lower numbers when testing on a chassis dyno. Wheel/tire size and weight will also impact chassis dyno results

Weather/Conditions – Temperature, humidity, altitude, and air density all impact engine performance. Heat, high humidity, and thin air will all work towards reducing engine output

Engine Health – Higher miles tends to result in increased build up and lower compression which can and will impact engine output. Properly maintained engines will have better performance than abused or neglected engines.

Supporting modifications – The highest power levels require supporting modifications. Depending on the engine, this could mean forged internals, built transmission, upgraded fuel system, 110+ octane race fuel, etc.
Stage: W.1 (Stock Vehicle) W.2 (Race Exhaust fitted)

Vehicle:
Please confirm:
NOT LEGAL FOR SALE OR USE ON POLLUTION CONTROLLED MOTOR VEHICLES
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Confirmation
Please confirm that you are not installing this product within the United States.

This policy only applies to installers and/or users who are in the United States, customers who reside in other countries should act in accordance with their local laws and regulations.

Some Weistec Engineering performance upgrades may solely be used on vehicles in sanctioned competition which may never be used upon a public road or highway, unless permitted by specific regulatory exemptions (such as a CARB E.O.). For state specific details please visit the following website. http://www.semasan.com/emissions

It is the responsibility of the installer and/or user of the product to ensure that it is used in compliance with all applicable laws and regulations. If a product was purchased in error, do not install and/or use it. The purchaser must arrange to return the product(s) for a full refund.

All performance modifications and installations are at the customer’s own risk. Weistec Engineering holds no responsibility either implied or otherwise for mechanical, electrical or other failure when using any aftermarket performance products.
$5,499.00 $5,499.00
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How To Tune
Prop 65 warning

Warning
This product can expose you to chemicals including carbon black, silica - crystalline, formaldehyde, and lead which are known to the State of California to cause cancer, and lead, which is known to the State of California to cause birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Product details

Weistec Horsepower	745
Weistec Torque	550
Manufacturer	Weistec
Street legal in all the US States	No
Engine Family	M840T
Stock Horsepower	612
Stock Torque	465
Tuning Method	Cypher Pro Dealer
Needs Unlock?	No
Pops & Bangs Available?	Yes
Auto Start/Stop Removable?	ECU
Induction Type	Turbocharged
Module Type	ECU
See more

Vehicle application

year	make	model	trim	engine
2026	McLaren	GTS	Base	Twin Turbo 4L V8 (M840T)
2025	McLaren	GTS	Base	Twin Turbo 4L V8 (M840T)
2024	McLaren	GTS	Base	Twin Turbo 4L V8 (M840T)
2023	McLaren	GT	Base	Twin Turbo 4L V8 (M840T)
2022	McLaren	GT	Base	Twin Turbo 4L V8 (M840T)
2021	McLaren	GT	Base	Twin Turbo 4L V8 (M840T)
2020	McLaren	GT	Base	Twin Turbo 4L V8 (M840T)
2019	McLaren	GT	Base	Twin Turbo 4L V8 (M840T)
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Product Description

The McLaren GT is proof of just how far the M840T platform can stretch. It's McLaren's first dedicated grand tourer, built on the same underlying architecture as the 720S but reworked specifically for comfort, with a carbon-fiber rear deck and glazed tailgate that open up meaningfully more luggage space than any other McLaren has ever offered. Its engine, a bespoke version of the M840T designated M840TE, is tuned for smooth, effortless delivery rather than an outright peak number, making a factory 620 PS, and its engine mounts are roughly half as stiff as the 600LT's to keep the ride genuinely refined. The same engine architecture that powers an extreme track hypercar also powers a car built for comfortably covering serious ground, which says a lot about how good that architecture really is.

Weistec's ECU calibration for the McLaren GT is a software recalibration of that factory M840TE. It's built to work with the comfort-oriented engineering McLaren already put into this car rather than override it. Factory protections, including knock control, thermal management, and OEM diagnostics, remain fully intact. Delivered with OEM-level validation, it takes this McLaren GT from a factory 612 hp and 465 lb-ft to 745 hp and 550 lb-ft, giving the most refined McLaren in the lineup a genuinely thrilling edge to go along with it.

How Do You Get Your McLaren GT ECU Tune Tuned?

Follow these steps — this is what your specific vehicle needs and supports.

Choose Your Tune Stage

Core Improvements

Standard with this tune

Increased Horsepower
Increased Torque
Improved Throttle Response
Optimized Fuel and Spark
Increased Boost
Top Speed Limiter Removed

Free Add Ons

Want it louder?

Want to stop the stopping?

Pick Your Tuning Method

See the full tuning process →

1Selected

Cypher Plus

Order a Cypher Plus and tune your car yourself from your phone, entirely through the MyFlasher app. Watch how it works.

1Selected

Cypher Classic

Order a Cypher Classic handheld and tune your car yourself.

2Selected — Pick return shipping at checkout

Mail It In

Remove your ECU or TCU and mail it to us for tuning. Required for some applications.

3Selected — Pick Will call at checkout

In Person

Bring your vehicle, or just your ECU/TCU, to our Anaheim, CA headquarters. Call 714-202-0005 or email sales@weistec.com to schedule.

4Selected — Order through your local dealer

Cypher Pro Dealer

Visit a certified Cypher Pro Dealer near you. Find one with our dealer locator.

Complete The Upgrade

An ECU tune alone won't remove all factory limits or fix how power reaches the ground. Add these to round out the upgrade with no limitations.
Read the full CPC & TCU breakdown →

What is a CPC module?

The CPC (Central Powertrain Control) is a separate control unit that manages things like the active exhaust valves, radiator fan, intercooler pumps, and speed limiter. On many newer Mercedes-Benz vehicles, it also houses torque limiters that can hold back an ECU tune from reaching its full potential.

What is a TCU tune?

A TCU (transmission control unit) tune delivers faster, firmer shifts with higher line pressure, reducing clutch slip and increasing the transmission's torque capacity. It's a worthwhile upgrade on its own, or paired with an ECU tune for a fully sorted powertrain.

Your Total

Good to Know

This is a reflash of your original module, not a stand-alone unit.
Power gains vary by vehicle, modifications, fuel, and operating conditions (ambient temperature, altitude, etc.).
New or upgraded spark plugs are always recommended when tuning.
Product may not be emissions compliant. Check local laws prior to installation.
Always use a battery charger during programming.

McLaren GT ECU Tune

Power gain Up To

Torque gain Up To