Subaru WRX (FA20DIT) Intercooler Upgrade Guide

The 2015–2021 VA Subaru WRX with the flat-four FA20DIT is a fantastic car that responds very favorably to performance mods. Previously, we ran an article about the best Downpipe/J-Pipe for the WRX (VA), and now we’re looking at intercoolers. Intercoolers are fantastic upgrades for those looking to keep their charge air temperatures down, which is crucial on a turbocharged engine like the FA20. In this guide, we are going to look at the benefits of upgrading your Subaru WRX intercooler, as well as the different options available. Read on to find out the best intercooler for the 2015–2021 Subaru WRX. 

Subaru WRX Intercooler Basics

First, let’s talk about what an intercooler does. The purpose of upgrading the WRX intercooler is to decrease the temperature of the air going into the engine. Turbochargers are powered by exhaust gasses from the engine, so they take on extreme amounts of heat. In addition, as air compresses it also heats up, so the boost (also known as charge air) that comes out of a turbocharger can get exceedingly hot. 

Intercoolers are located in the intake system between the turbocharger and the engine. They cool the post-turbo air after it has become compressed, removing heat and adding oxygen before it enters the engine. Colder air has more oxygen than warmer air, so it produces more horsepower and torque. 

Upgrading your intercooler on the WRX gives you improved cooling efficiency and recovery time compared with the stock unit. The stock intercooler on the FA20 is adequate for factory power levels, but it quickly becomes over-matched at anything above. In addition, the stock unit does not stand up well to repeated pulls and becomes heat soaked rapidly in the summer. A larger intercooler rectifies both of these issues, keeping charge air down even after multiple runs. 

Like many other vehicles, the Subaru WRX with the FA20 utilizes an air-to-air intercooler. It is top-mounted over the engine, which is where the car’s iconic hood-scoop comes into play. Ambient air enters the engine bay through the hood-scoop and washes over the intercooler. This cools down the intercooler and helps prevent it from heat soaking, and allows it to cool the charge air. 

Subaru WRX Intercooler Design and Location

Intercooler upgrades on the Subaru WRX can generally be classified in two categories: Either front-mount intercoolers (FMIC) or top-mount intercoolers (TMIC). TMICs are what the WRX comes with stock. They fit directly onto the stock location on the WRX and bolt up to the OEM charge pipe and throttle body. In contrast, FMICs relocate the intercooler to behind the front bumper of the car, directly in front of the radiator. They also replace the OEM charge pipe and usually do not fit the OEM intake.

In terms of performance, adequately sized FMICs will almost always outperform TMICs. 

WRX Top Mount Intercoolers

First up are top-mounted intercoolers. TMICs are much easier to install on the WRX because they retain all the factory intake components. They also utilize the factory hood scoop for cooling within the engine bay.

Top-mount intercoolers are also going to be much less expensive for the WRX than front-mount intercoolers. The cores on TMICs are typically smaller than FMICs, mainly due to size constraints inside the engine bay. Due to their location, top-mounts also utilize much less piping than front-mounts for the FA20DIT. This reduces the amount of area the charge air has to travel before reaching the engine, which cuts down on lag. 

WRX Front Mount Intercoolers

Now, let’s talk about Front-mounted intercoolers. FMICs are a much more involved install than top-mounts, and typically require some extra modification to the bumper. Front-mounts usually do not connect cleanly to the factory intake system, so they also often require the purchase and install of a new intake. In addition, to fit the WRX the inside of the bumper usually needs to be cut and trimmed to accommodate the core.

FMICs also have much more piping than TMICs, which increases lag slightly as the charge air has longer to travel. To make up for it, FMICs generally have larger cores than top-mounts and provide increased efficiency over them.

Probably the biggest advantage of switching to a front-mount intercooler is going to be its ability to combat heat soak. Since they sit in front of the engine – not on top of it – FMICs stay considerably cooler than TMICs. This helps prevent heat soak and leads to improved cooling and lower intake temperatures for the FA20.

WRX – TMIC vs FMIC: Which is right for me?

There are several important considerations to keep in mind when deciding between a TMIC and a FMIC. Price is going to be the biggest difference, as FMICs are much more expensive than TMICs on the WRX. Front-mounts also usually require both the purchase of a new intake and modification to the bumper, as well as the replacement of the OEM crash protection bar, which can be a safety issue.

Front-mount intercoolers are much better at fighting heat soak than top-mount intercoolers. TMICs sit on top of the engine, so they collect heat constantly and can become heat soaked easier. FMICs sit in front of the engine and radiator, so they do not take on nearly the same amount of residual heat. The opening of the bumper is also larger than the hood-scoop, which allows FMICs better access to cooler ambient air, too.

On the WRX, most TMICs are actually incredibly effective, making the difference between them and FMICs not quite as pronounced. Typically for the FA20, a TMIC and FMIC will be equal for the first few pulls and runs. It’s with prolonged use – like on the track – that a FMIC will really shine. On most daily driven and weekend warrior WRXs, a TMIC intercooler will suffice. For those looking at regular track days (Auto-X, Rally, Rally-X, Time Attack, etc.), you might want to consider an FMIC for the dog days of summer. 

FA20 WRX Intercooler Upgrade Benefits

Benefits of Subaru WRX intercooler upgrades include:

• +10-45 horsepower
• +10-30 lb-ft of torque
• More sustained performance
• Reduced charge air temperatures
• Reduced heat soak
• Detonation and Pre-ignition prevention

The biggest benefits you will see tangibly from a WRX intercooler upgrade are going to be increases in horsepower and torque, as well as reduced intake temperatures. Peak power increases will be somewhere around 10-25 horsepower and torque without any tuning. With tuning, you can see as much as 45 horsepower and 30 lb-ft of torque gains.

However, getting an equivalent tune with your intercooler is where you will really start to see benefits. Due to the increased cooling of a larger intercooler, tuners can run higher levels of boost and ignition timing without seeing detonation. This means that not only will peak power rise, but the entire power band will see gains, increasing average horsepower, too. 

Apart from higher power numbers, you’ll also see lower charge air temperatures – which is what is responsible for the increased power. With heat soaking, the delta between charge air temperatures and ambient air temperatures can sometimes be as high as 50-60°. A larger intercooler will considerably reduce this, usually to within 10-15° of ambient – if not to ambient temperature itself. 

This means that your engine is getting the coldest possible air it can (you cannot cool below ambient with just air). As we mentioned, colder air means more oxygen and less detonation and pre-ignition. The hotter your climate the more an intercooler upgrade will come in handy. 

Best FA20 WRX Intercooler Upgrades

Alright, now that we have a good understanding of intercoolers and their benefits for the WRX, let’s look at our recommendations for the best FA20 WRX intercoolers on the market. This list includes both top-mount and front-mount intercoolers, with top-mounts coming first.

This is not a comprehensive list of intercoolers for the VA WRX, but these are the top options in terms of craftsmanship, price, and performance. These intercoolers will fit all years of the VA WRX, from 2015-2021.

1) Subaru WRX GrimmSpeed TMIC w/ Splitter

Price: $889.00

Design: Top-Mount

The top choice on our list for TMICs is the GrimmSpeed Top-mount intercooler for the FA20 WRX. Anybody who is familiar with Subaru knows that GrimmSpeed is hands down one of the top American made brands, and their TMIC is an absolute beast. It features a 13.1” x 10” x 3.75” Cross Flow Core with a fully integrated two-piece splitter. It has cast aluminum end tanks and includes a pre-drilled bung for easy water/methanol system integration.

The WRX GrimmSpeed TMIC can give FA20 10–25 horsepower without a tune, and 15–35 horsepower with a tune. Its fitment and craftsmanship are excellent, and the integrated splitter replaces the stock unit with one that’s much more efficient. Intake temperatures are reduced by as much as 40° when compared with the stock unit.

GrimmSpeed products are all 100% made and manufactured in Minnesota and utilize TIG welded construction. Their FA20 WRX TMIC is one of the best, if not the best TMIC on the market, and is at a great price-point. I personally installed and used this intercooler on my WRX for several years and it performed outstanding. 

2) Subaru WRX Garrett Motion Top-Mount Intercooler

Price: $700.00

Design: Top-Mount

Our second ranked top-mount intercooler is the Garrett Motion FA20 WRX Top-Mount Intercooler. Garrett is one of the premier aftermarket and OEM turbo manufacturers, and their intercooler technology is also top-notch.

The Garret TMIC for the FA20 WRX features a 13″ x 10.2” x 4” core capable of up to 530 hp. It is 70% larger than stock and can produce gains of up to 16 horsepower and torque. Users should see reductions of intake temperatures by as much as 30° under WOT. It is also great at recovering between WOT runs and during multi-gear pulls.

The Garret TMIC won’t offer the same performance as the GrimmSpeed, but it is considerably cheaper. It is a fantastic budget option for those looking to upgrade without breaking the bank. Used ones can often be had for only $400–500 in the classifieds.

3) WRX Cobb Tuning Front-Mount Intercooler

Price: $2,025.00

Design: Front-Mount

Our first front-mount intercooler on the list is the Cobb Tuning FA20 WRX Front-Mount Intercooler Kit. Cobb is an internationally acclaimed performance company, and they are probably the most well known manufacturer for Subaru performance parts. Lots of their popularity is due to their Accessport ECU tuner, but their hardware parts are also top notch. 

The Cobb WRX FMIC features a huge 24″ x 11″ x 4″ core with 2.5” piping. It is capable of absolutely massive horsepower gains,  but it still works efficiently on mid-range builds. It is compatible with the Cobb Big SF Intake only, so you have to get them as a package. Unlike many WRX FMICs, the Cobb unit does not require any modification to the bumper, only to the undertray on the WRX.

One of the biggest selling points for the Cobb front-mount is that it is 100% CARB compliant. Users can expect gains of as much as 45 horsepower with a tune, as well as a reduction in charge air temperatures to nearly ambient.

4) Subaru WRX GrimmSpeed FMIC

Price: $1,559.00 – $1,878.00

Design: Front-Mount

In addition to their TMIC, we also have GrimmSpeed FA20 WRX Front-Mount Intercooler Kit  on the list. It features a massive 27” x 11” x 4″ Cross Flow Core that can support small, medium, and big horsepower builds. The GrimmSpeed FMIC has the largest core available of all our listed intercooler kits. 

The GrimmSpeed front-mount intercooler will fit the FA20 WRX’s stock intake or the GrimmSpeed intake. Users can expect as much as 35–40 horsepower with an accompanying tune, as well as a reduction in intake temps by up to 40°. GrimmSpeed is known for their incredible fitment and workmanship, and their FMICs are top of the line.

5) WRX FA20 PRL Front-Mount Intercooler

Price: $1,295.00

Design: Front-Mount

The next entry on our list is the PRL FA20 WRX Front-Mount Intercooler Kit. PRL was one of the first companies to produce FMICs for the VA WRX, and their units are very well reviewed and have been used on many high horsepower builds. 

PRL’s FMIC measures to 22″ x 12″ x 3.5,” and is capable of producing as much as 600 horsepower. They claim some pretty incredible gains with their FMIC over the stock TMIC. Without a tune, they claim as much as 40 horsepower along with vastly improved midrange gains. With a tune and basic supporting mods, they claim as much as 60-75 horsepower over stock – though that’s a little bit more questionable. 

The PRL is the best bang for your buck FMIC on the list. It is the least expensive and still provides excellent gains, and it is recommended by many top tuners. Though they were discontinued for a few years, in early 2023 PRL announced they would be making more of them. 

6) Subaru WRX ETS FMIC Upgrade

Price: $1,554.00 – $2,104.00

Design: Front-Mount

The final entry on our list is the ETS FA20 WRX Front-Mount Intercooler Kit, and it is one of the most proven on the list. ETS, like PRL, produced one of the earliest FMIC kits, and they have been used on several iconic and huge horsepower builds. The first 9 second Subaru WRX with the FA20 featured an ETS FMIC.

The ETS core is huge, 26” x 11.37”, and has options for 3”, 3.5” or 4” thickness. You can also get an optional titanium brushed piping kit for increased cooling on the cold side. Users can easily expect 30–35 horsepower gains from the FA20 using the ETS FMIC, and should see intake temperature reductions of up to 40°.

Subaru WRX FA20 Intercooler Upgrade Summary

An upgraded intercooler is a fantastic performance and reliability mod for the FA20 Subaru WRX. Not only are the horsepower and torque gains significant, but intercoolers also reduce the potential for heat soak and allow for more consistent and sustained performance. Reducing heat soak decreases the likelihood of serious engine problems like misfiring, pre-ignition, or knock, which greatly increases engine longevity.

Anyone running higher than stock power levels or living in a hot climate should seriously consider an upgraded intercooler for their VA WRX. Benefits will not be as prominent in the winter, but in the summer they are very noticeable and can help save your engine. Utilizing a tune in combination with your intercooler is the best bang for your buck and offers the biggest gains.

The two top-mount intercoolers on our list, the GrimmSpeed and Garrett, are both solid options. The GrimmSpeed is a little more expensive but offers better performance and cooling. Of our front-mount intercoolers, the PRL is the best budget choice while still offering great performance. The Cobb and GrimmSpeed FMICs both offer similar performance, but the GrimmSpeed is cheaper and has the largest of all the FMIC cores. The ETS is the most tried and documented FMIC for the FA20 WRX, and is notable for being a part of some iconic builds.

They are all designed to fit all years of VA WRX (2015-2021), so the real question becomes between a top-mount or a front-mount. Top-mounts are easier to install and are cheaper, but offer less performance and resistance to heat soak on the FA20DIT.

What’s your experience with Subaru WRX VA intercooler upgrades? Are you considering one?

Leave a comment and let us know!