Ultimate Guide To A Modified 4th Gen Subaru WRX (2014-2021)

Ultimate Guide To A Modified 4th Gen Subaru WRX (2014-2021)

The 4th Generation Subaru WRX, produced from 2014 to 2021, is known for its wicked performance and handling. Equipped with a turbocharged 2.0L or 2.5L flat-four engine, the WRX delivers between 268 to 305 horsepower, depending on the model year. Its all-wheel-drive system and advanced suspension make it a popular choice among driving enthusiasts and is a beloved platform for people looking for a deal. 

Only problem is, most people really mess up modifying these things. Either parts are wrong, engines blow up, or even worse, it looks bad. We offer a mess of performance upgrades specifically designed for the WRX but we want to help you mod it the right way; not the easy way. So with that said, let’s jump in.

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Basics About Modifying The Subaru WRX

From simple bolt-on upgrades to more extensive modifications, there are various ways to customize the WRX to suit your preferences. Whether it’s adding more power, improving the suspension, or upgrading the interior and exterior, understanding the basics of modifying the Subaru WRX is essential for anyone looking to make their car stand out on the road or track. From understanding the benefits of different aftermarket parts to the importance of working with reputable tuners and shops, this guide will cover everything you need to know about modifying the Subaru WRX to unleash its full potential.

Factory Issues & Reliability Problems With 4th Gen Subaru WRX

Common factory issues and reliability problems associated with the 4th Gen Subaru WRX include oil consumption and starvation issues. Sorry, but have to tell you. The engine’s don’t have good tolerance to bad mods or bad owners. Many owners have reported excessive oil burning, which can lead to potential engine damage if not addressed proactively. The oil starvation problem, where the engine does not receive sufficient lubrication, can result in catastrophic engine failure. Make sure your oil pan is baffled and your compression is good before anything else. 

To address these issues, it is essential to prioritize regular maintenance items such as oil changes and inspections before modifying the Subi. This includes using the recommended oil grade and quality, as well as checking for any leaks or signs of oil consumption. It is also important to monitor oil levels regularly and address any abnormal consumption immediately.

In addition, upgrading to aftermarket oil cooling systems and using oil catch cans can help mitigate these problems. Ensuring proper installation and maintenance of these aftermarket components is crucial for long-term reliability. By taking these recommended actions and staying proactive with maintenance, owners can minimize the impact of these oil issues and ensure the longevity and reliability of their 4th Gen Subaru WRX.

Poor Oil Circulation

If you suspect poor oil circulation in your vehicle, start by removing the oil filter and inspecting it for any clogs or metal particles that could be blocking oil flow. Next, use a pressure gauge to test the output of the oil pump and visually inspect the bearings and gears for signs of wear or damage. Look for any burn oil or metal shavings that could indicate a problem.

To address poor oil circulation, it is also recommended to install an oil baffle pan and oil catch can. These mods are essential for this platform as they help to prevent oil starvation and improve oil flow throughout the engine.

Boost Spike Issues

Boost spike issues on the 4th gen Subaru WRX can be addressed by first evaluating the functionality of the wastegate. A malfunctioning wastegate can cause erratic boost levels, leading to boost spikes. Inspecting the intercooler system for leaks is also crucial, as any leaks can result in pressure loss and erratic boost levels. Additionally, checking for a malfunctioning diverter valve specific to the 4th gen Subaru WRX is important, as a faulty diverter valve can cause inconsistent boost pressure.

Remember, the best way to modify a car is to start with a clean car. 

Best Modified Subaru WRX Parts

There, we got the crappy part of this talk out of the way. Seriously, do the basics first and make sure you’ve got a clean, ready to modify turbocharged engine. It’ll save you so much hassle. We’re going to break it down into suspension mods, wheels, tires, intercooler, cooling, exhaust, and common exterior mods. Keep in mind that if you’re looking for performance gains that are affordable or even cheap, you’re going to want to be very careful. We always urge people to keep in mind that quality stuff is usually a dime more than the cheapest thing you’ll find, but it’s worth it.

Aftermarket Coilovers & Suspension for Subaru WRX

The Subaru WRX is a high-performance rally-inspired sedan known for its all-wheel-drive capability and impressive handling. Don’t ruin that with crappy suspension. These cars need coilovers that have consistent damper behavior and enough travel to utilize the deep wheel wells. When it comes to upgrading the suspension, our top options include the BC Racing BR Series Coilovers or Fortune Auto 500 Series Coilovers.

BC Racing BR Series Coilovers – This series offers an affordable entry into coilover suspension without sacrificing performance, comfort, build quality, vehicle height, or handling. It’s a well-rounded choice for those looking to upgrade from stock suspension​​. You get damper adjustment, ride height adjustability, and some other goodies. For around $1,195, it’s hard to beat BC Racing.

Check out BC Racing Here

Want to learn more about BC Racing Coilovers? Read about them in our article “Are BC Racing Coilovers Any Good?

Fortune Auto 500 Series Coilovers – This series is a single adjustable coilover and the entry model into the Fortune Auto lineup. You get high flow digressive technology, 24 step rebound adjustable dampers, T6 6061 mounts and camber plates, along with a 5 year limited manufacturer’s warranty. For around $1,799, you’re paying more, but getting more.

Check out Fortune Auto Here

Which one should you buy? We’ve found the best availability and “speed” with BC Racing. They have LOADS of stock, strong prices that work for almost every budget, and won’t let you down. We’ve found the best success with Fortune Auto when you’re really looking to buy a coilover set “forever.” They’re modular, you can grow with them and fine tune them, and we have enjoyed their more race-focused functionality over BC Racing. But we’ve run both and have both and love both.

Best Wheel & Tire Fitment For Subaru WRX

For the Subaru WRX, the best wheel and tire fitment options include high-performance tires from top brands such as Michelin, Continental, and Toyo. When it comes to wheels, some top options include the Konig Ampliform, Enkei NT03+M, Kansei KNP, and Stage Wheels Knight. You can go with wider wheels here and the aftermarket options are endless because of Subaru’s 5×114.3 bolt pattern. We recommend sticking with something that’s a lightweight wheel, can be paired up with a sticky tire, and has space for those big brakes.

Check out Konig Wheels

Check out Enkei Wheels

Check out Kansei Wheels

Check out Stage Wheels

For Continental tires, you can purchase them together with wheels from MartiniWorks, ensuring a seamless and convenient process. Yeah, that’s a plug. But we do this for a living. We also know how to work around fitments that require a bit of finesse. That includes the wide stuff, the skinny stuff, and everything in between.

Wheel Size And Tire Guide for 4th Gen Subaru WRX (2014-2021) – These are the top fits we recommend with coilovers. These fitments will give you a properly looking car that don’t take away from you using the car fully.

18×9.5 +22 Wheels with 225/40/18 Tires (Kansei Tandems Featured)

18×9.5 +38 With 265/35/R18 Tires (Enkei RPF1 Featured)

18×9.5 +40 With 245/35/R18 Tires (Enkei NT03 Featured)


Choosing the right wheel and tire fitment for the Subaru WRX is crucial for optimal performance and style. By considering high-quality options from Enkei, Konig, Kansei, Stage Wheels, Michelin, Continental, and other top brands, WRX owners can ensure an exhilarating driving experience.

Intercooler & Cooling Modifications

There are several intercooler and cooling modifications available for Subaru WRX and WRX STI models, including front mount intercoolers, aftermarket intake systems, and upgraded cooling systems. Brands like Mishimoto offer a variety of performance cooling upgrades specifically for these vehicles.

Upgrading intercoolers and cooling systems can offer several benefits for Subaru WRX and WRX STI owners. Front mount intercoolers, for example, provide improved cooling efficiency, reducing the intake air temperature and increasing the density of the air entering the engine. This leads to improved engine performance, with a potential increase in power delivery and overall handling. Aftermarket intake systems also contribute to better airflow, resulting in improved throttle response and potentially increased horsepower. Keep in mind, FMIC’s or TMIC’s are REQUIRED for tuning. While some may mark it as optional, it really isn’t and should be considered if a tune is sitting in a cart somewhere on the internet. 

For cold air intakes, we recommend something from AEM, Afe, Perrin, or GrimmSpeed. This performance modification is going to be a fun one, because it makes the car just sound good. 

Additionally, upgraded cooling systems can help maintain optimal engine temperatures, especially under heavy load or high-performance driving conditions. This can prevent overheating and potential engine damage, providing peace of mind for drivers who push their vehicles to their limits.

Overall, investing in intercooler and cooling modifications for Subaru WRX and WRX STI models can greatly enhance the engine’s performance, power delivery, and overall handling, making it a worthwhile upgrade for enthusiasts looking to get the most out of their vehicles.

Tunes For Your Subaru WRX

Tunes can be done on stock engines or fully built ones. Our biggest recommendation is to always tune your Subaru WRX with any change to air, fuel, cooling or engine management. Failure to do so can cause the engine to perform “out of variance” and ultimately deteriorate its already sensitive shelf life. In the JDM market, popular turbo upgrades include the Garrett GTX3071R or the Blouch Dominator 1.5XT-R with specific specifications such as a 3inch inlet and 8cm2 exhaust housing. For injector upgrades, the Subaru WRX can benefit from the Injector Dynamics ID1000 or the DeatschWerks 1000cc fuel injectors for increased fuel delivery. Perrin Performance also has some options for you.

Best Sounding Exhaust Subaru WRX

Looking to upgrade your Subaru WRX’s exhaust system? Here are the top 5 aftermarket exhaust manufacturers and models available at MartiniWorks. First up, the Invidia Q300 offers a deep, smooth tone with minimal drone and improved flow for better performance. Priced at $800.

Next, the Borla S-Type provides a more aggressive, throaty sound with enhanced power and torque. This model is priced at $1800.

The Remark Axleback exhaust delivers a distinctive, deep rumble with improved airflow and a more pronounced boxer engine sound, priced at $550.

The Cobb Tuning cat-back exhaust offers a unique, aggressive growl with noticeable power gains and retails for $1,100.

Lastly, the Nameless Performance cat-back exhaust system provides a deep, rumbly tone without overwhelming noise, also offering improved flow and performance, priced at $750.

These aftermarket exhaust systems not only enhance the unmistakable burble of the flat 4 boxer engine but also contribute to improved engine performance with their unequal length headers and reduced restriction, giving your Subaru WRX that iconic sound and added power. Buy your Subaru exhaust from MartiniWorks for the best deals and top-quality products.

Exterior Mods For Your 4th Gen Subaru WRX

When it comes to exterior mods for your 4th Gen Subaru WRX, there are plenty of options to choose from. For carbon fiber aero, Seibon is a popular choice, offering high-quality body kits, spoilers, and canards to give your WRX a sleek and aggressive look. Perrin is another reputable brand known for its custom grilles and other exterior enhancements, allowing you to personalize the front end of your car.

If you are looking to upgrade your headlights and taillights, companies like Spec-D and Anzo offer stylish and modern options to improve the overall appearance of your WRX. These aftermarket options often come with LED or halo features to make your ride stand out even more.

In addition to these popular options, there are numerous other brands and products available to customize the exterior of your 4th Gen Subaru WRX. However, Seibon and Perrin are widely recognized for their high-quality and diverse range of exterior mods, making them top choices for enthusiasts looking to enhance the look of their WRX.

Common Mistakes Modifying A 4th Gen Subaru WRX

When modifying a 4th Gen Subaru WRX, it’s important to be aware of the common mistakes that many enthusiasts make. From choosing the wrong aftermarket parts to neglecting crucial maintenance, these errors can lead to performance issues and costly repairs. By understanding and avoiding these mistakes, you can ensure that your modifications enhance the car’s performance and longevity.

Failure to Tune The Engine

Failure to properly tune the engine can result in a range of negative consequences. One potential consequence is decreased fuel efficiency or the small fact they blow up.

Don’t mod this one without a tune plan in place. Simple as that.

Installing Mods on a Failing Motor

When a motor is failing and not taken care of appropriately, it may experience power losses, flat spots, erratic idling, timing issues, and fuelling issues. At this point, the temptation may be to install modifications in an attempt to boost the motor’s performance. However, this can actually accelerate the motor’s decline.

Modifications can put additional strain on an already struggling motor, exacerbating existing issues and potentially causing new ones. For example, adding a turbo or supercharger to a motor with timing or fuelling issues can further exacerbate these issues, leading to a more rapid deterioration of the motor. Similarly, modifications that increase power output can put additional stress on components that are already weakened, leading to further failures.

Instead of attempting to mask a failing motor with modifications, it is important to address the underlying issues causing the decline. Proper maintenance, timely repairs, and addressing any existing problems are critical to extending the motor’s lifespan. Ignoring these issues and simply adding modifications will only accelerate the motor’s failure.

Proper Maintenance

To ensure the proper functioning of the fourth generation Subaru WRX, it is important to perform regular maintenance tasks. Pushing this stuff off just hurts you more, trust us.

If you need to learn the maintenance schedule of your Subaru WRX; check out Cars101 here.

Build Threads of 2014-2021 Subaru WRX’s | MartiniWorks

Want to learn from people who already built their Subaru WRX? Check out our car build threads, right here on MartiniWorks. Each build thread has a story, mod list, photos, videos, and history on how the build went. We picked some of our favorites below to take a peek at otherwise you can check out the full build thread page here!

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Alex Martinez

My name is Alex, or Alex Martini (Alex.Martini__) and I love building unreliable cars. From track, road, drag and drift, there really isn't a motorsport I love. PS if you're reading this, just know that we've got some WILD builds coming for MartiniWorks that we're really excited to share with you :)