Subaru Impreza WRX Gen3 Tuning

"All you need to know about tuning the Subaru Impreza WRX Gen3 engine!"

As many of our forum members have asked about the Impreza WRX Gen3 and recommendations on how to modify one, so we've created an article to cover the primary areas which make for improvement and tuning success on this great car.

The third generation of the Subaru Impreza-based WRX vehicles was offered between the years 2007 and 2014.

Here we take a look at some of the performance modifications that can be performed on these cars for increasing their power and torque.

Now we will outline options for your Impreza WRX Gen3 tuning and summarise the greatest mods that work. Subaru Impreza WRX Gen3 make a good tuning project and with the best motorsport parts like remaps, turbo upgrades and camshafts you will definitely improve your driving pleasure.

We have articles covering tuning, mods and upgrades for the following models.

Subaru Impreza tuning, Impreza WRX STi mods, Impreza WRX Gen1 mods, Impreza WRX Gen 2 mods, Impreza WRX Gen 3 mods, Impreza WRX Gen 4 mods, Impreza WRX Gen 5 mods, (VA) WRX Mods

History of the Impreza WRX Gen3 Engine

Subaru revealed both the gasoline and diesel engine versions of its third generation Impreza at the New York Auto Show in 2007. The wagon was replaced by a hatchback. Both narrow and wide versions of a sedan (2008) and hatchback (2007) were included in this generation named GE (narrow sedan), GV (wide sedan), GH (narrow hatchback), and GR (wide hatchback).

Five gasoline engines (1.5 L EL15 H4, 2.0 L EJ20 H4/H4-T, and 2.5 L EJ25 H4/H4-T) and one diesel engine (2.0 L EE20 H4-T) were included in the Impreza models the WRX was based on, along with 4/5-speed automatic and 5/6-speed manual transmissions.

These gasoline engines were rated at 107-170 hp while the diesel engines were rated at 150-227 hp. The diesel-powered turbocharged performance variant of the third generation can sprint from zero to sixty mph in 5.8s comparing very favourably with the gasoline performance variants in this class.

This model got criticism for its soft suspension leading to the arrival of the new updated WRX-S model in the UK. It received an output boost to 265 hp and a sprint time of 4.7 seconds.

WRX STI models were fitted with a 2.0 L EJ207 engine with a twin-scroll turbocharger providing a power output of 304 horsepower. STI got a facelift for the 2011 model with noticeable tweaks to the suspension, a new front bumper, and wider tires. Subaru launched various editions of this STI model like Subaru WRX STI Takumi, WRX STI spec C, WRX STI A-Line, WRX STI R205, WRX STI Special Edition, and Cosworth WRX STI CS400.

Subaru has launched WRX STI 330S version for the UK market. This version got specific tuning by Prodrive and generated an increased engine power to 375 horsepower.

Subaru Impreza won the ‘AMI Insurance performance car of the Year’ award in 2010. Impreza won the ‘IIHS TopPick Plus’ award in 2013 and the ‘National Business Review Sports car of the Year’ award in New Zealand in 2014.

Tuning the Subaru Impreza WRX Gen3 and best Impreza WRX Gen3 performance parts.

Best Impreza WRX Gen3 tuning parts

Thinking about the best modifications for your Impreza WRX Gen3 engine, we are going to concentrate on the upgrades that realizes the best value for your outlay.

 

Tuning tips and articles

 

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

 

Please watch our video which covers the 5 principles of tuning your Impreza WRX Gen3. Be sure to keep up with our latest YouTube content and subscribe.

Best mods for your Impreza WRX Gen3

  • Remaps - Impreza WRX Gen3 engine tuning/remapping offers the most advantage in terms of your investment, aftermarket ECUs, and inline Tuning boxes are all alternatives.
  • Turbo Mods - Adding a turbocharger is the most dramatic method to increase air supply, this means you are able to burn more fuel and make higher power. Notably one of the most expensive modifications it does provide the largest gains.
  • Performance Camshafts are are often the best upgrade for an engine, but should always be fitted by someone who knows what they are doing and it is often hard to find a suitable cam near you but you'll probably find a local firm to regrind a stock cam for you.
  • Brake Upgrades - Improve your ability to stop needs to be near the top of your Mods list.
  • Intake Upgrades and Exhaust - Please be warned on their own these mods will NOT ADD PERFORMANCE , but they will enable you to lift power after other upgrades by removing the restriction.
  • Flowing and porting the Head - Head work will get air flowing into the engine while removing turbulence or restrictions.
  • Low mass flywheel - a reduced weight flywheel will improve the engines free revving nature. In some cases flywheel lightening is not suitable for all Impreza WRX Gen3 engines.
  • Impreza WRX Gen3 Suspension Upgrades - Adding a Suspension Kit radically improves your Impreza WRX Gen3 handling Poly Bushes and Coilovers are typically fitted to achieve this

Impreza WRX Gen3 Tuning Stages

Typical stage 1 mods often include: Suspension (mild drop), Drilled & smoothed airbox, New Bushes, Intake manifolds, Panel air filters, Performance Brake Pads.

Typical stage 2 mods often include: high flow fuel injectors, Fast road cam, Suspension (Sports), Sports catalyst & performance exhaust, Brake Discs (drilled/slotted or grooved, fuel pump upgrades.

Typical stage 3 mods often include: Twin charging conversions, Crank and Piston upgrades to alter compression, Competition cam, Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting.

Impreza WRX Gen3 Handling/Suspension Upgrades

Upgrades to the Impreza WRX Gen3's suspension and handling

One of the most popular reasons for tuning your Impreza WRX Gen3 suspension is to better its handling. In spite of this, we regularly witness the same mistakes over and over again.

No matter how fast your vehicle is, if the ride quality is not good, you won’t be able to fully enjoy the experience.

Suspension plays a key role in determining the ride quality of your vehicle. So here are a few important suspension-related upgrades that you can perform on your third-generation Subaru Impreza-based WRX vehicle:

Lowering Kits

Lowering kits, as the name implies, are used to reduce the ride height of vehicles. These not only make the vehicle look great, but they also lower the car's centre of gravity, making it easier to corner.

Lowering kits are offered for third-generation WRX vehicles by the following manufacturers:

  • Eibach;
  • Megan Racing;
  • H&R;
  • Yellow Speed Racing.

Coilovers

Coilovers are the best suspension-related performance upgrades for your vehicles. You can choose these parts from one of the following companies:

  • ISR Performance;
  • BC Racing;
  • HKS;
  • Godspeed Project.

Is there anything I should bear in mind while deciding on suspension upgrades for my Impreza WRX Gen3?

Uprated Bushes

What factors should you consider when setting up and selecting your bushes if your Impreza WRX Gen3 is also used as a daily driver?

The suspension components of the Impreza WRX Gen3 may be connected to the car's chassis through bushes, which are rotatable rubber mounts. These rubber ones will start to fail as they wear out.

Brand New OEM rubber bushes may have a major impact on the performance of your vehicle.

It's probable that the ride may be a touch rougher because of the stronger polyurethane bushings but they'll last longer and maintain tighter handling.

Worn bushes may also quicken the degradation of other suspension components due to the increased vibration and play.

With a new set of poly bushes, the excessive play associated with rubber bushes may be lessened.

You may struggle to find a full set of poly bushings, but most stores have the primary mounts available. Custom polyeyurothane bushings are often made to your requirements.

A frequent misconception is that the best setup would be a non-adjustable suspension system that lowers the vehicle by 80mm purchased from a franchised component shop.

Vendors may claim that their Impreza WRX Gen3 suspension kits are compatible with any or all model year Impreza WRX Gen3s.

For a vast variety of vehicles, a 'compromized' approach is obviously incorrect.

How low should you go on the Impreza WRX Gen3?

TorqueCars research and testing indicate that the maximum suspension drop for most road vehicles is 23 - 44 millimetres, whereas the maximum suspension drop for versions that come with lowered suspension already is 18 millimetres.

These tolerances may be drastically lowered if the wheel size is changed. Even with 16 or 17-inch wheels and conventional suspension, lowering the vehicle may create a a slew of new issues.

Brake Mods & Upgrades

Brakes are essential for high-performance vehicles because once you reach a high speed, you must maintain control of your vehicle to avoid an unfavourable situation.

Without a proper braking system, no matter how fast your vehicle can go, you will be hesitant to push it to its limits because you will be unsure of its ability to stop.

Normally the following braking components are upgraded on vehicles:

  • Brake Pads;
  • Brake Rotors;
  • Brake Kits.

Let’s see the different options available to you for your third-generation Impreza-based WRX and STI vehicles.

Brake Pads

Brake pads are an essential component of any braking system. Choosing high-quality parts is a great way to ensure that your vehicle has impressive stopping power.

The following companies offer brake pads for these cars:

  • Power Stop;
  • Stop Tech;
  • EBC;
  • Hawk.

Brake Rotors

You can also use brake rotors from the following companies:

  • R1 Concepts;
  • Stop Tech;
  • EBC.

Impreza WRX Gen3 Camshaft Upgrades

Getting a fast road cam will raise the upper RPM range power and are better suited on petrol engines, than diesels. Most cars will see peak power gains through performance camshafts on most engines.

Significant gains on the Impreza WRX Gen3 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

Fast road cams commonly boost the bhp through the rpm range, you may lose a little low down torque but the higher rpm power will be higher.

Motorsport cams, boost the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a road car you need to match your bhp range to your preferences.

You will never find a Impreza WRX Gen3 Competition camshaft is at all pleasant when in heavy traffic. The low end idle will typically be lumpy and irregular, and this is something you'd notice on a track when you drive in the upper third of the rpm band, but on roads this is a serious issue and we've heard from lots of drivers regretting their decision to install a more extreme competition cam profile to their engine.

Some Impreza WRX Gen3 engines respond differently primarily due to the airflow when cams are fitted depending on the cam being more or less aggressive cam durations and cam duration as unique due to manufacturing tolerances and quality variations so check your engine on a rolling road.

The ECU mapping and fuel delivery and fuel pump also will say much on the bhp gains you'll hit.

A longer valve duration can amend the bhp curve, and on most engines there are some advantages to extending the intake or exhaust durations and valve lift.

Carefully think through your options and then source your parts and set yourself a power target to save yourself from expensive mistakes.

ECU Mapping Improvements for the Impreza WRX Gen3

Remaps helps fully realize the full potential of all the modifications you've done to your Impreza WRX Gen3.

(Sometimes chip tuning the ECU is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but check it has knock protection and that you get it installed right.) It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but the end result may differs on the modifications you've carried out and the condition of your engine.

The performance of a vehicle can be quickly improved by using the process of chip tuning. Several companies offer their services in this regard. GAN Tuning is one of these companies.

Considering the 2.5-litre WRX STI as an example, the car already has around 300 hp which can be further improved with a little help from GAN. You have two options in this regard which are:

  • GAN GTL
    Power increase: 65 hp; Torque increase: 90 Nm.
  • GAN GT
    Power increase: 76 hp; Torque increase: 106 Nm.

The best part about this chip tuning process is that several companies guarantee that not only will the vehicle's performance be significantly enhanced, but that the vehicle's fuel efficiency will also be considerably improved.

GAN's service includes 18 mappings, which is a big number. Aside from that, most service providers in this field provide an impressive warranty to give you peace of mind.

When it comes to performance chip modules, several companies offer these components. Here are a few of them:

  • SmartTune;
  • JDM;
  • GTE;
  • PLP+.

Air Flow improvements on the Impreza WRX Gen3

It is vital to any performance tuning job to push air and fuel into your Impreza WRX Gen3

Intake manifolds flow the air during the suck phase from the filter and allow it to be drawn into the engine cylinders.

Shape and flow rate of the Intake manifold can make a substantial change to fuel mixing and power on the Impreza WRX Gen3.

Commonly we find the inlet manifolds are needing motorsport parts, although some OEM provide reasonably well designed plenum chambers.

Air intake systems are typically one of the first modifications performed by performance vehicle enthusiasts.

This is because these air intake systems are very efficient in enhancing the flow of air to the vehicle's engine.

Vehicle owners are interested in increasing the flow of air to the engine because this air, along with fuel, is used in the form of a mixture in internal combustion engines.

For the 2.0 litre variant of the third generation Impreza-based WRX models, you can choose the air intakes of one of the following brands:

  • PERRIN Performance;
  • TurboXS;
  • AMS.

For the 2.5 litre version of these vehicles, you can go for one of the following companies:

  • Mishimoto;
  • Takeda;
  • AEM Intakes;
  • K&N;
  • GrimmSpeed.

These air intakes are quite expensive, but they are one of the most effective performance upgrades for your car.

Adding a Impreza WRX Gen3 big valve conversion, carrying out port work and head flowing will also improve bhp, the fantastic side effect is it will raise potential for raising the bhp increase on other tuning parts.

These air intakes are quite expensive, but they are one of the most effective performance upgrades for your car.

Adding a Impreza WRX Gen3 big valve conversion, carrying out port work and head flowing will also improve bhp, the fantastic side effect is it will raise potential for raising the bhp increase on other tuning parts.

Impreza WRX Gen3 Turbo upgrades

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes excellent power gains.

An excellent way of increasing the power of your vehicle is to add a turbocharger.

The WRX and STI versions of the vehicle were offered with turbochargers by Subaru.

However, still, for some reason if you want to upgrade the turbocharger on your vehicle, you can choose an aftermarket part from one of the following companies:

  • GrimmSpeed;
  • BorgWarner.

The GrimmSpeed JB400 turbocharger kit is a vehicle-specific part whereas if you want to choose a universal turbocharger, you can go for the BorgWarner AirWerks Series S200SX turbocharger.

The universal part is nearly half the price of the vehicle-specific turbocharger from GrimmSpeed.

It is worth noting that turbochargers are some of the most expensive performance upgrades for your vehicle and thus special care should be taken while fitting them.

However you'll find engines have limits. Discover these restrictions and install higher quality crank and pistons to utilize the power.

It's not unheard of mechanics spending a stack of money on turbocharger upgrades on the Impreza WRX Gen3 only to experience the engine go up in smoke soon after it's been completed.

Large capacity turbochargers often suffer no power at low rpm, and low capacity turbochargers spool up more quickly but don't have the peak end power band gains.

We are pleased that the world of turbochargers is always moving on and we are seeing variable vane turbochargers, permitting the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbochargers divert the exhaust flow into 2 channels and push these at differently angled vanes in the turbocharger. They also boost the scavenging effect of the engine.

It is common that there's a limit in the air flow sensor AFM/MAP on the Impreza WRX Gen3 when a lot more air is being sucked into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped performance at a much lower level.

Adding a supercharger or secondary turbo will make large torque gains, although this setup is more complex to get working. We have this guide to twinchargers if you want to read more.

Intercooler Upgrades

An intercooler is the next modification that has to be on your list of upgrades for your third-generation Impreza-based WRX if you want to get serious performance from your vehicle.

The purpose of an intercooler is to provide dense cold air to the engine. That’s because such air is rich in oxygen.

As oxygen is required for the combustion process, the greater the quantity of oxygen, the larger the amount of power and torque produced.

That’s why we highly recommend getting a high-quality intercooler for your vehicle.

The following brands offer intercoolers for the third-generation Subaru Impreza WRX:

  • Mishimoto;
  • PERRIN Performance;
  • HKS.

Radiator & Engine Cooling

Once you start getting enough power from your vehicle, the next major problem that is encountered by almost all performance vehicle enthusiasts is the dissipation of heat.

That’s because the stock cooling systems in most vehicles are only designed to handle the heat produced during normal operation.

As excessive combustion produces a lot of heat, an aftermarket high-performance radiator is required to handle it.

Some of the manufacturers that offer performance radiators for the third generation Subaru Impreza-based WRX STI vehicles include but are not limited to:

  • Mishimoto;
  • Skunk2;
  • Koyo.

These are moderately priced parts and getting one of them installed in your high-performance vehicle is a great idea.

Fan Shrouds
Experts suggest getting fan shrouds installed on your WRX STI if you want to increase the flow of air to the vehicle’s radiator.

This aids in quickly dissipating the heat from the radiator and by doing so, the vehicle can continue to deliver high performance for long periods.

Impreza WRX Gen3 Fuelling Upgrades

You will need to ensure that the engine is not starved of fuel so must look at the fuelling when you start extending past 20% of a bhp increase. Fuel pressure boost valves raise the fuel pressure, providing a more snappy throttle response.It makes sense to over specify your injectors flow rate.

The accepted safe increase is to add 20% when fitting an injector, this allows for injector deterioration and provides a bit of spare capacity should the engine need more fuel.

The fuel delivery system is critical to a vehicle's performance. If the fuel delivery is not up to the requirements, no matter what upgrades you install on your car, the result will fall short of your expectations.

This is why, after you've installed an air intake system, a turbocharger, and an intercooler, you should think about upgrading your car's fuel delivery system.

Some of the most commonly upgraded fuel delivery parts for Subaru Impreza WRX STI vehicles of the third generation include, but are not limited to:

Fuel Rail Kits;

High Flow Fuel Pumps;

Fuel Injectors;

Fuel Pressure Regulator;

Injector Driver.

Let’s see the companies that offer these parts for your third-generation Impreza-based WRX STI.

Fuel Rail Kits

You can choose the fuel rail kits from:

  • COBB;
  • Perrin;
  • DeatschWerks.

High Flow Fuel Pumps

High-flow fuel pumps are extremely important for modified vehicles. So, choosing one from a well-reputed brand is essential. Here are some of the well-set brands in this regard:

  • Walbro;
  • DeatschWerks.

Fuel Pressure Regulator

The following companies offer high-quality Fuel Pressure Regulators for the third-generation Subaru Impreza-based WRX STI models:

  • Perrin;
  • Hybrid Racing;
  • AEM.

Fuel Injectors

Fuel injectors are one of the most critical components of the fuel delivery system. These injectors control the amount of fuel delivered to the engine for the air-fuel mixture that generates power.

The amount of fuel delivered by these injectors determines the power generated by the engine. Fuel injectors for your WRX can be purchased from one of the following companies:

  • COBB;
  • DeatschWerks;
  • HKS;
  • Injector Dynamics.

Choose the fuel injectors carefully as they determine the output of your vehicle. If you end up choosing injectors that don’t supply enough fuel to the engine, the vehicle will not be able to produce the required amount of power.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

Impreza WRX Gen3 Performance Exhausts

Only look to replace your exhaust if your current exhaust is actually causing a flow problem.

On most factory exhausts you'll find the flow rate is ok even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Now that your vehicle is generating a lot of power and the overheating issue has also been taken of, the next aspect that needs your attention is the exhaust system.

You might be surprised to know that the exhaust system of your vehicle also determines the power produced by the car.

As a result, installing an aftermarket exhaust system allows more exhaust gases to easily exit the engine. This helps to keep the overall set-up at a lower temperature.

For the WRX and STI vehicles, you can choose the exhaust system from one of the following companies:

  • GrimmSpeed;
  • Turbo XS;
  • Invidia;
  • XFORCE Exhaust;
  • MagnaFlow.

For road going cars mods such as a sports catalyst pretty much remove this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

And will allow the full exhaust flow due to it's higher internal surface area and design.

The alternative test pipe mod or catalyst removal should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars (and in some you can't even replace a working catalyst).

Alloy Wheel Upgrades

Wheels
The wheels on your car improve the appearance of your vehicle. Here are some of the companies that offer wheels for third-generation Impreza-based WRX vehicles:

  • Enkei; 
  • SSR;
  • Gram Lights.

Weak spots, Issues & problem areas on the Impreza WRX Gen3

The Impreza WRX Gen3 engines are pretty solid and give little trouble as long as they are well maintained.

Carbon build up in the head, particularly around the valves which will reduce power, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on intake clean to remove carbon build up By avoiding short journeys where the engine doesn't warm up and using good quality fuel you can reduce this risk.

Frequent oil changes are essential on the Impreza WRX Gen3, especially when tuned and will help ensure reliability of the engine.

If you want to learn more, or just get some friendly advice on Tuning your Impreza WRX Gen3 engine please join us in our friendly forum where you can discuss Impreza WRX Gen3 tuning options in more detail with our Impreza WRX Gen3 owners. It would also be worth reading our unbiased Subaru tuning articles to get insights into each modification and how effective they will be.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our readers have got up to and which upgrades work best for them on each model of car. We use your comments and feedback to improve the accuracy of these Impreza WRX Gen3 tuning guides which get regular updates and revisions.

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