Leon Tuning

"Getting the best performance from your Seat Leon."

One of the first major releases from SEAT to be produced under the watchful eye of VAG and certainly an impressive release.

The Leon was released in 2000 and was constructed by the VAG group.

Combining the Latin flair of Seat with the build quality of Volkswagen it shared much with it's brother the Golf. As relatives, they've shared platforms, engines, gearboxes, electronics, and switchgear. Leon's strategy is to undercut the Golf on price while giving uncomplicated enjoyment, punchy style and,  more, at least for the hotter versions, performance. Because the Leon uses cheaper plastics and lighter components than the Golf it performs better in most like-for-like tests.

The Leon can be considered a fun rival to the golf sharing the range of engines from the 1.4 up to a heavily tweaked 1.8l 20 valve Turbo.

Later TFSi engine options really sparkle and bring out the full potential of the Leon chassis.

The Seat Leon is available in a variety of bright fun colors with red and yellow remaining the popular choices.

Performance wise the model to go for has to be the Leon Cupra, which was released with 180bhp AUQ engine code, there was a 210bhp model AMK engine code, and this later a heady 225bhp with the arrival of the BAM engine code, leaving both the A3 and golf looking a bit power shy.

Also there were some pretty impressive diesels which came in 110, 130 and 150bhp variants there are also some Cupra diesel versions.

Tuning tips and articles

Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums


The obvious engine choice is the 1.8T and the later 2.0 TFSi and this can stand phenomenal tuning without major internal modifications. A larger turbo along with an intercooler upgraded Dump valve and tune/remap could produce power gains of up to 300 BHP on the 1.8T. Remaps on the 2.0 TFSi sees power hiked to around 280bhp!

The following modifications are usually performed by our members, decide how far you want to go before you begin.

Getting the right mods for your planned usage of the car is vital. Stage 3 (competition) mods just don't work well on the road.

Please watch our video which covers the 5 principles of tuning your car. Be sure to keep up with our latest YouTube content and subscribe.

Best Engine Mods for your car

    1. Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
    2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
    3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
    4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
    5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

Typical stage 1 mods often include: Exhaust, Panel air filter, Engine Tunes/Remapping, lighter flywheel (Front mounter intercooler on Turbo models)

Typical stage 2 mods often include: Ported and polished head, Fast road cam, fuel injector & fuel pump upgrades,power clutch, KO4 turbo conversion

Typical stage 3 mods: Engine balancing, upgrading forced induction (turbo/supercharger - twicharging), Internal engine upgrades (pistons/head/valves), competition cam, sports gearbox.

Because of the popularity of this engine there are a number of VAG specialists springing up with a standard tuning packages which can be applied.

Sharing the Audi and VW engines means there are so many tuning options.

The standard performance and handling is a very good although many owners will lower their car 30 millimetres and fit slightly stiffer springs to help eliminate body roll.

Larger wheels will look nicer but can really hamper the handling so stick with 16 or 17's and use low profile tires to retain the cars original rotational diameter. Large heavy wheels really will hamper the cars handling and cornering abilities.

From a performance point of view we should not ignore the diesel range which included the 1.9 TDi which produces 110 BHP. With a relatively cheap tune/remap you can see power levels of 160 BHP and still retain much of the fuel economy of the standard model. (The power gains on the 2.0 and 2.5 diesel engines are even better!)

Later diesel engines respond even better to engine tuning/remapping and you will generally see better fuel economy as well. Just expect to service the car more frequently though.

All the diesel models respond really well to remapping giving 30% more power and 15% better economy. We've seen the diesels pushed to 220bhp on stock internals although the smaller turbos run out of puff around 180bhp.

Remapping your Leon

What is it about OEM maps that makes them so bad?

Manufacturers do not want customers to be inconvenienced by mechanical or fuel efficiency difficulties, which is why they design vehicles with a very large margin of safety.

Due to the fact that different countries utilize different gasoline grades and have varying degrees of weather conditions, fudging the map is essential to ensure that all autos operate correctly abroad.

The power of each vehicle varies by up to 10bhp depending on the component quality and installation. Rather of tailoring timing maps for each vehicle, they use a one-size-fits-all approach that works well for all Leons coming off the assembly line.

Therefore, if you are willing to maintain your Leon in top condition and use only high-quality fuels and components, you will discover that tunes or remaps significantly boost engine power.

Additionally, the average TorqueCars reader will be upgrading components, making a tune/remap a reasonable option. Anyone considering an engine upgrade should consider remapping.

All modern turbocharged engines benefit from tunes or remaps that increase power by 20%-30%. TorqueCars strongly recommends engine tuning/remapping turbocharged vehicles and doing this procedure on a rolling road/dyno to maximize power improvements.

How much does it cost to operate a vehicle that has been remapped?

Regularly service your car, perhaps reducing the period between services. A map tailored for high-octane gasoline will need the repair of components that break as a result of the increased workload. More power puts additional strain on components such as air flow sensors.

Months after a remap, a vehicle's weak points appear.

Typically, a tune/remap will uncover turbocharger and clutch difficulties. Additionally, turbos may fail, necessitating the maintenance of crucial components such as pistons and bearings.

Remaps on the NASP?

Without a turbo, a tune/remap will only add a few BHP (10% is normal), so unless you've made several modifications, notably cams, pistons, increased compression, engine balance, air intake, exhaust, head work, and larger valves, a tune/remap is not really worthwhile.

Protection for turbocharged engines A tune/remap commonly provides boost at lower engine speeds, causing the turbo to spin faster and hotter.

If you do not allow the turbo to cool, the oil in the turbo may deteriorate, necessitating a costly turbo repair. Additionally, installing a turbo timer will assist in cooling the engine.

Comparing remaps: Buyers BEWARE!

Be suspicious of engine tuning/remapping firms who make grandiose claims about their peak power output.

To attract attention, tuners have been known to induce a power blip or surge so they can quote a higher power figure!!

Take note of the graphic above; rather than delivering power across the complete torque curve, the more impressive-sounding 200bhp chart (shown in red) has simply a single power blip, with poor performance throughout.

However, the green trace suggests a consistent increase in power throughout the RPM range, which, although only 175bhp, is much more than the factory map and far more than the 200hp map.

Additionally, it displays peak power at 4000rpm, which is excellent for an engine that reaches its redline at 7000rpm.

We want to see a smooth torque rise with no dips or troughs on a map.

Let's see how power gains on your modified Leon affect your quarter mile times

We are assuming a 1400kgs kerb weight, & Manual transmission

Base power Quarter
115hp 18.27 140hp 1400kg 17.50
140hp 17.15 175hp 1400kg 15.95
150hp 16.77 225hp 1400kg 14.71
170hp 16.10 640hp 1400kg 10.98
550hp 1200kg 10.97

SEAT Leon exhaust system improvements

Replace your exhaust system only if it is causing you performance problems. While the majority of factory exhausts will flow smoothly with modest power improvements, if you want to go much farther, you'll need a more flowing exhaust.

Exhausts designed for racing may aid in increasing engine airflow, however a broad exhaust may reduce flow velocity.

At all times, maintain a thickness of 1.5-2.5 inches. Without the need for an illegal catalyst removal, an aftermarket performance catalyst may be able to restore that lost power, enabling the vehicle to stay legal to run on public roads.

Because the larger size and surface area of a sports catalyst bypasses this limitation and allows the vehicle to perform normally without a catalyst, it is comparable to modifying the test pipe while maintaining street legality.

This means that a sports catalyst increases performance to the level anticipated of a car without a catalyst while maintaining street legality.

Because removing a catalyst is unlawful in the majority of locales and areas (and in some, even replacing a functioning catalyst is illegal), the alternative catless mod or catalyst removal should be regarded an off-road-only modification.

Volkswagen Leon Turbo Upgrades and Modifications

The VAG company has introduced a range of turbocharged engines to its cars in recent years, so let's have a look at these turbocharged engines, their differences, and the best upgrade options. Read our comprehensive guide on VAG group turbochargers.

Additionally, we examine turbo power limits. You may exceed a turbo's safe operating limitations, but the turbo's life will be shortened. You will hear a whining or siren sound prior to the turbo failing, followed by smoke.

You should attempt to replace it at this point. A turbo failure may result in considerable engine damage, especially if a compressor fails.

Which turbochargers were installed in the Leon?

Comparison of the K03, K03s, and K04 The K03 turbo was available from 1996 until 2000, when it was superseded by more powerful K03s.

Engines The 1.8T AGU engines are equipped with K03 turbochargers. These engines use a mass air flow sensor and a cable-operated throttle in conjunction with smaller injectors. K03 turbochargers are used in AUM engines equipped with MAF and MAP sensors.

These engines include an improved drive-by-wire throttle configuration, which improves response time, fuel economy, and performance. Stigan and BorgWarner are two of the largest manufacturers of K03 turbochargers.

Differences between a KO3/KO3s

The most notable difference between turbos is the number of blades. The K03 has eleven, whereas the K03s has eight.

Normally, the actuator used to open the turbine bypass valve is a 65N or 85N, although select models had a two-port actuator.

Due to the increased boost pressure generated by 180hp engines, they need higher-quality actuators with a greater opening force. Numerous hybrid turbo manufacturers improve power using a larger compressor on the intake side.

Horsepower wise the K03 has the least energy, but with the proper upgrades, it is capable of 190 horsepower. You may get more, but your turbo will last longer.

The K03s is a more powerful version of the K03. The majority of individuals get 215 horsepower with K03s, which is within the safe range. Exceptionally, this turbo has been rated at over 250 horsepower, indicating that there is ample room for error.

The K03s provides a safe performance boost of at least 25 horsepower over the K03, and maybe more if you're prepared to shorten turbo life or do more maintenance.

How does the K04 compare to the K03 & K03s?

K04 Provides Outstanding Performance In comparison to the K03 and K03s, the K04 is larger and generates more power. The K04's performance can approach 350 horsepower when equipped with the proper gear, however the KO4's safe maximum is about 220hp.]

K03s and K03S turbocharged engines were smaller than K04. Despite its lower output, they took up less space than the K04 when fitted.

VAG's New Turbochargers

The IHI IS12, IS20, and IS38 turbochargers are the newest generation of turbochargers for the VAG K03, K03s, and K04 engines. The 1.8t MQB engines used by Audi and VW are IS12 stock turbocharged, whilst the IS20 utilises 2.0t MQB engines. Why IS38 Turbo?

The IS38 is renowned for its 370 horsepower (with the proper add-ons).

Due to its high reliability, it is a highly sought-after turbo from IHI. Additionally, the IS38 turbocharged engine is standard on some performance models such as the VW Golf R, Arteon, S3, and TTS.

As a result, the IS38 is an excellent choice for anyone seeking superior performance and longevity.

Additionally, the IS38 produces significant turbo power at higher RPMs and is a bolt-on turbo.

Numerous hybrid models include improved housing and impeller designs for higher performance.

A High-Performance Replacement for the IS12/IS20

Numerous automotive enthusiasts have upgraded their IS12 and IS20 turbocharged engines to the IS38. Turbo-Charged Upgrade

Why Should You Upgrade your Leons Turbocharger?

The following are some of the reasons why people change or upgrade their turbos: Upgrades to a vehicle's turbocharger are one of the most significant power adders.

Turbos degrade in performance with time and must be replaced. Newer turbos provide extra add-on options and use cutting-edge technology.

Leon Turbo Upgrades at Their Finest

We encourage you to do thorough due diligence on your supplier, since there are several counterfeit and low-quality turbo units on the market. Install a low-cost turbo upgrade and you'll be back to square one doing it again in six months. Additionally, selecting a turbo with the following additional features is a good idea:

      • Aluminum compressor wheel (light and strong)
      • Larger impellers/turbines (Maximizes the boost available)
      • A motorized actuator (sharpens throttle response and maximizes your power gains)

These little details may make or ruin a project.


If this is not done, lean running or limp home mode with error codes may result. A factory ECU will only slightly lower fuel consumption, and you will be wasting the opportunity.

If you need to replace the conventional turbo, the following choices are available: K03 exchanges If you want to upgrade your vehicle's stock K03 turbo, the following are some choices to consider:

SG SKU 40-30002 SKU 40-30002 SKU 40-30002 SKU 40-300

BorgWarner 53039880029 SKU 40-30002

TorqueCars highly advises you to use BorgWarner turbochargers in your Leon project.

This turbocharger is often found on or comparable to the following vehicles: - 1997-2006 1.8 liter Audi A4 1.8 liter Volkswagen Passat 1998–2004 Rebuilds of VW Passat 1.8L Gasoline K04

Several alternatives exist for replacing the standard K04 turbo:

Stigan 847-1435 SKU 40-30002 SH

This Stigan High-Performance New Turbocharger is compatible with the following vehicles: 1997-2006. VW Passat 1.8 liter Audi A4 1.8 liter 1998-2004

AW BorgWarner 53049500001 SKU 40-30003

The following cars are compatible with this BorgWarner Airwerks Series High-Performance New Turbocharger: Audi TT 2000 (all) Volkswagen Leon 1.8 liters 2000 1.8 Jetta

Genuine IHI Turbocharger 2001 If your factory-installed IHI turbocharger fails, the SKU 9VA02 may be used to replace it.

This turbocharger should be compatible with the following vehicles. Leon Golf Jetta Passat. While companies are constantly updating their turbos, changing a turbo is not as simple as it seems.

It is identical to swapping a VAG turbo to a different model. While the technique varies each automotive, numerous steps may involve the following:

      • Replaced fuel injectors
      • Changing the diameter of the exhaust pipe
      • The fuel Used - high octane/cetane helps
      • A newly designed booster controller
      • Intercoolers or other forms of cooling
      • A wastegate modification
      • Utilization of less constricting catalysts
      • Alternative high flow mufflers

While the following list may seem onerous at first sight, the duties necessary differ according to the vehicle. Apart from the aforementioned factors, the engine compartment design and layout have an effect on how difficult it is to transfer a turbocharger from another model.

There may be a need to reroute the exhaust and intake pipes, and space may be restricted.

Leon Turbo Hybrids

Why Are There Hybrid Superchargers? While Stigan, IHI, and BorgWarner all manufacture turbochargers, many persons believe that hybrid turbochargers should be designed.

They produce hybrid turbochargers by combining high-performance components from many manufacturers. These hybrid turbochargers are designed to outperform factory-installed turbochargers.

How Do Hybrid Turbochargers Compare With OEM Turbochargers?

To achieve extreme performance, a hybrid turbo may have a single component or the whole OEM turbo replaced. Hybrid turbos are unique in that they do not have serial numbers. While these turbochargers seem to be factory-installed, the upgraded internal components promise considerable performance gains.

Improve your Leons Performance With Hybrid Turbochargers

Due to the fact that hybrid turbos combine the best of the greatest characteristics, they exceed regular turbos in terms of response and performance.

A well-designed hybrid turbo boosts pressure and flows well while maintaining a safe turbine speed.

This prolongs the life of the components. You get what you pay for with hybrid turbos. While stock turbos need several compromises, the primary advantage of hybrid turbos is that you get what you pay for.

Constraints to bear in mind

With mods and well-executed REMAP K03s Should generate 210-220 horsepower with a Stage 1 tune/remap (air filter, exhaust, and bolt-on upgrades).

Stage 2 engine tuning/remapping (catalytic converter replacement, fuel system optimization, and intercooler modification) may result in 230-250 horsepower.

Bear in mind that a Stage 2 engine tuning/remapping needs an intercooler to cool the air; otherwise, the power output would be significantly reduced.


Stage 1 improvements provide around 250-260 horsepower to the K04 turbo, however, we have seen some with more.

A more powerful high-pressure fuel pump; an upgraded FMIC (front mount intercooler); premium gasoline (98+ Ron); and a high-performance clutch (your OEM clutch will slip).

Remapping of the IHI IS38;

With the addition of a Decat Exhaust*, this turbocharger can be tuned/remapped to 370 horsepower, making it ideal for Audi Seat Skoda and Volkswagen enthusiasts! The IS38 turbocharger for Audi and Volkswagen vehicles gives best-in-class performance after remapping.

Other Modifications

Because Leon's body panels are robust and sturdy, adding a carbon fiber bonnet and front wings might result in significant weight savings.

Generally, the first Leon change to do is to arrange the suspension. Dropping the automobile 30-40 millimeters and installing stronger springs will sharpen the ride and increase the driver's pleasure of the vehicle.

Many Leon owners prioritize improving their vehicles' handling with suspension improvements; this will undoubtedly boost your pleasure of the car.

We discovered that the majority of Leon factory suspension settings need modification; a few degrees of toe out for cornering or toe in for stability, -0.8 to 1.3, and a touch of negative camber improves cornering and handling substantially.

Drop the vehicle by up to 26mm - 39mm and install performance firmer dampers; larger drops will often need further modifications.

By sourcing brakes from the VR, Audi RS3, and Porsche, you can ensure that your braking problems are addressed by an OEM. Large discs and pads significantly improve the Leon's braking responsiveness.

Front wheel drive models perform better when equipped with a limited slip differential or a semi-locking differential similar to that seen on the Audi A3 T Sport. Additionally, lower gear ratios boost acceleration.

Feel free to browse our tuning articles and if you require any more detail on the modifications we have recommended use our forum to ask a model specific questions. You will also meet other enthusiastic seat tuners and be able to swap tips and ideas with them.

Please Check out my YouTube channel, we're regularly adding new content...

PLEASE HELP: I NEED YOUR DONATIONS TO COVER THE COSTS OF RUNNING THIS SITE AND KEEP IT RUNNING. I do not charge you to access this website and it saves most TorqueCars readers $100's each year - but we are NON PROFIT and not even covering our costs. To keep us running PLEASE Donate here

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Feedback - What do You Think?

Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article, I really want to improve this article with your help and suggestions.

Please watch this video and subscribe to my YouTube channel.

Member Benefits

Join our forum today and benefit from over 300,000 posts on tuning styling and friendly car banter.

You will also have full access to the modifed car gallery, project car updates and exclusive member only areas.

(All car owners of all ages and from all countries are welcome).

BMW 335i - 2021 COTY

We gave the BMW 335i our coveted car of the year award, read more about this awesome car and see why 335i Tuning Guide

Tips for N54 Tuning

Tips for N55 Tuning
Tips for B58 Tuning

Popular articles

Diesel tuning
Remapping ECU
double de clutch
Induction Kits
Customize a car
Chipping cars
Modified Car insurance
Track day insurance cover
Remap Diesels
MPG calc
Unblock a DPF
Stage 1-3 Tuning

Surge Tank

Fuel surge tanks

Tuning Boxes

Tuning boxes

De Badging Cars

debadging cars – taking the badges off a car

De Locking

Delocking a car how to delock a car

Overfill Oil Problems

Overfill Oil Problems

Lpg Conversions

Benefits of conversion to LPG fuel in Cars

MPG Calculator

MPG calculator UK miles per Gallon – calculate MPG