MISHIMOTO MMAI-STI-15
MISHIMOTO MMAI-STI-15
MISHIMOTO MMAI-STI-15

MMAI-STI-15P

Mishimoto® (15-17) WRX STI Race Cold Air Intake System with Heat Shield

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Compatible: (2.5L)

2015 - 2017 Subaru WRX STI

 

Filter re-oil is not included in Lifetime Warranty.Heat Shield: Steel, Black Powder-Coat


Add some horsepower to your 2015-2017 STI with the new Mishimoto Performance Air Intake. This kit is engineered specifically for your 2015-2017 Subaru STI and includes everything needed to replace the restrictive stock airbox.

Our engineers spent months fine-tuning this design in an attempt to squeak out every last bit of performance. This dyno-proven air intake provides 20 whp/18 wtq gains over the stock intake while maintaining safe air/fuel ratios, perfect for some extra punch on the street or autocross course. The Mishimoto Subaru 2015-2017 STI Performance Air Intake includes everything needed for installation, installs in under one hour, and works perfectly with the stock tune. The mandrel-bent aluminum intake pipe is available with a red or black powder-coated finish or a polished aluminum finish. This pipe utilizes the Mishimoto air straightener and CNC-machined mass airflow sensor (MAF) housing to provide accurate and consistent MAF readings, which translates into a smooth power band. To reduce air intake temperatures (IATs), the air filter has been placed outside the hot engine bay, and a powder-coated heat shield prevents any heat-soak from occurring. The Mishimoto free-flowing air filter provides a 16% greater surface area, optimal airflow, and proper filtration of dirt and debris. The included Mishimoto oiled air filter is completely serviceable, allowing for a lifetime of reliable use.

Additionally, this kit includes a silicone coupler, clamps, and all other hardware necessary to complete a quick installation for easy bolt-on power. A rubber cap is provided to place over the sound symposer housing. Along with an upgrade in power, this intake also provides an aggressive and rich intake tone that is a huge improvement over the stock intake. The Mishimoto Subaru WRX/STI Performance Air Intake is designed in Delaware, USA and includes the Mishimoto Lifetime Warranty.

  • Direct fit for 2015-2017 Subaru STI
  • Maximum gain: 20+ whp and 18 wtq
  • Mandrel-bent aluminum pipe offered in polished, wrinkle black, and wrinkle red
  • Includes heat shield to protect air intake from hot engine heat
  • Rubber cap supplied for noise generator
  • Designed in Delaware, USA and filter made in USA
  • Mishimoto Lifetime Warranty
  • CARB EO #: D-759-3

 

VEHICLE SPECS

ENGINE CODES EJ257
CHASSIS CODES VA
FITS 2015-2021 Subaru STI


PRODUCT SPECS

PIPE DIAMETER 2.75"
OILED FILTER 38 g of oil on filter
PIPE MATERIAL 38g of oil on filter
OIL COLOR Red
HEAT SHIELD MATERIAL Steel
CAUTION Under normal driving conditions, hydrolock is unlikely. If the filter becomes submerged during flooding, the engine may ingest water. Mishimoto recommends avoiding these conditions, or re-installing your stock intake system, if your area is prone to flooding.
MAX GAIN 20+ whp and 18 wtq
AIR FILTER PART NUMBER MAF-2757

 

PURCHASE INCLUDES

(1) Aluminum Intake Pipe
(1) High-Flow, Oiled Filter
(1) Heat Shield w/ Protective Edging
(1) Silicone Coupler
(1) Rubber Mounting Isolator
(1) Sound Generator Cap
Hardware
Mishimoto Lifetime Warranty

 

MISHIMOTO 2015+ SUBARU STI PERFORMANCE COLD-AIR INTAKE SYSTEM, PART 2: PROTOTYPE FABRICATION

Prototype Fabrication

After experimenting with some boxed designs in Part 1 of this write-up, it was time to turn our attention to a shrouded setup, similar to what we offer for the 2008–2014 models. We’re hoping we could utilize the piping from our existing kit, which is well designed and has proven power gains. After placing the shroud into position, we found that it would certainly fit, but would require some modification. The fabrication work began! Check out a few shots taken during the process.

Mishimoto intake shroud modification
Mishimoto intake shroud modification
Mishimoto intake shroud modification
Mishimoto intake shroud modification
Mishimoto intake shroud modification
Mishimoto intake shroud modification

Once all fab work was completed, we had a functional shroud that we could use for testing purposes. We could also use this shroud to develop a 3D model for our production units. Take a look!

Mishimoto modified intake shroud
Mishimoto modified intake shroud
Mishimoto modified intake shroud
Mishimoto modified intake shroud
Mishimoto intake modified shroud
Mishimoto intake modified shroud

We could then combine this shroud with our intake pipe, shown below, to capture some performance data.

Mishimoto intake pipe
Mishimoto intake pipe

This pipe features a stock MAF housing, as well as an air straightener to provide laminar flow across the sensor.

Check back next time for a look at the testing process, and the results from our dyno pulls! Check out the teaser shot of this car getting setup on the dyno!

2015 Subaru STI on dyno
2015 Subaru STI on dyno

 

MISHIMOTO 2015+ SUBARU STI PERFORMANCE COLD-AIR INTAKE SYSTEM, PART 3: TESTING

Time to see what kind of power gains we are able to achieve with our intake design! First, we strapped this Launch Edition to the dynamometer.

2015 STI on the dynamometer
2015 STI on the dynamometer
2015 STI on the dyno
2015 STI on the dyno

Then we began making pulls. On our first day we tested only the stock intake system. Once complete, we installed the Mishimoto intake system and sent the vehicle out for some road testing. We wanted to allow the ECU to adjust to the new intake before making our pulls. After well over 150 miles of road use, we returned the next day to compile dyno data for the Mishimoto intake.

2015 STI on the dyno
2015 STI on the dyno

Testing Results

So how did we do? Well, I think the plots below summarize our results quite well.

2015 STI dyno plots
2015 STI dyno plots

As you can see, our intake made a great impact on performance, especially at the upper end of the rpm range. The biggest gains occurred from around 5,000 rpm to redline. We saw peak power increases of nearly 20 whp and around 6 wtq. We also saw maximum gains of 22 whp and 17 wtq.

With our past intakes that make power on the stock tune, we have had a few inquiries regarding engine longevity, AFRs, and knock. Our AFR charts for the runs above are shown below.

2015 STI AFR plots
2015 STI AFR plots

Although leaner than the stock curve, we are still well within a safe range for engine operation up through redline. Also, we experienced zero counts of knock during our dyno and road testing. These results were expected and are similar to those from our 2008–2014 intake system.

Intake Shroud Design

Now that we had positive testing results, we could move forward with producing our STI-specific shroud to get this product on the market! Check out a rendering of the design in 3D!

Mishimoto intake shroud render
Mishimoto intake shroud render

 

MISHIMOTO 2015+ SUBARU STI PERFORMANCE COLD-AIR INTAKE SYSTEM, PART 4: RACE INTAKE SYSTEM

As noted earlier in this article series, we would be tackling a race intake system to go along with our bolt-on unit. So what makes the race system different? For this particular system we are using a larger-diameter intake pipe with a larger MAF housing. This means greater intake flow, but it also means it will no longer function with the factory tune. This system is meant specifically for drivers who want aggressive professional tunes so they can take advantage of airflow modifications such as larger turbochargers and high boost pressures.

Because the 15’ model shares the EJ from the previous generation, we would be using the same intake pipe and filter as we did with our 2008–2014 kit. This unit is shown below.

Race intake pipe
Mishimoto air filter

Here is a look at this system fitted to a 2010 STi!

Mishimoto 2008–2014 Race Intake installed

So, all we truly needed was to design an airbox that would accommodate this pipe and function with the body of the new 15’ model.

We hit Solidworks and came up with the design you see below!

Mishimoto 2015 STi Race Intake rendering
Mishimoto 2015 STi Race Intake rendering
Mishimoto 2015 STi Race Intake rendering
Mishimoto 2015 STi Race Intake rendering

 

 

Warranty:

 

Based on 23 reviews
83%
(19)
4%
(1)
4%
(1)
4%
(1)
4%
(1)
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