Grimmspeed StealthBox Cold Air Intake Red Subaru WRX 2015-2021

Rated 5.0 out of 5
Based on 12 reviews
SKU: grm060067
Availability: Out Of Stock
Type: Intake Cold Air
Regular price
$399.00
Regular price
$399.00
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Subtotal: $399.00

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Inspiration for the StealthBox Intake came from internal discussions about what we wanted from an intake system for the 2015+ WRX. Of course performance is the highest priority, but at GrimmSpeed so much more than that goes into a product. We wanted an intake that purred quietly under normal driving circumstances, but would roar at wide open throttle. We wanted an intake that looked at home in the well-sported 2015+ WRX engine bay instead of a shoebox stuffed into the fender area. From here, the SteathBox was born. We took the concept one step further and referenced the F-117 Nighthawk as inspiration for the stealthy look of the GrimmSpeed heat shield. It should come as no surprise that the performance it packs is equally unique.

Part #: 060067

Quick Specs

  • +32wtq (14.3%) and +21whp (9.6%)
  • Designed in CAD - Perfect mating with the factory turbo and ram-air scoop
  • Low bend angle aluminum tube - Minimize restriction and maximize performance
  • Shielded MAF sensor placement - Protects MAF from heat, which increases accuracy of readings
  • Made in the USA - Manufactured right here in Minnesota

Design

MAF diameter and placement, total bend angle, filter location, and heat shield design were the primary variables during the design phase. To ensure accurate readings, unaffected by the intense heat of the engine bay, MAF sensor placement absolutely must be within the heat shield. To minimize restriction, it was important to keep the total bend angle in the intake tube as low as possible, but still raise the filter location away from the ground to protect it from the elements. Lastly, testing showed the importance of utilizing the factory ram air scoop to feed the otherwise stagnant air in front of the fender.



Our engineers created a 3D model of the intake system and fender area in order to optimize each of these variables. The result is an intake with a total bend angle of 74 degrees, and a filter that is placed neatly within the fender, such that it offers protection from the elements without being unnecessarily exposed to the heat of the engine bay. Lastly, the shape of the heat shield follows that of the factory air scoop, feeds the filter with fresh air evenly and promotes swirl which prevents pockets of motionless air on the cold side of the shield.

We have made the decision not to sell the intake without the heat shield. It seems that others have done this to hit a lower price point at the cost of performance. We'd prefer that everybody using a GrimmSpeed StealthBox Intake have the best possible experience and the use of the heat shield is critical to the function of the intake system.

Materials and Fabrication

Each intake begins with a CNC bent and laser cut 6061 Aluminum tube. Contrary to popular belief, particularly from those producing composite intakes, we found that the increased thermal mass of using thicker aluminum tubing (1/8” wall thickness) kept the intake from being vulnerable to rapid temperature change. This is called the ‘thermal flywheel effect’ and will keep the rapidly fluctuating temperatures inside your engine bay from affecting intake temps as drastically.

Custom MAF flanges are machined from the same 6061 alloy and are placed on the straight nearest the filter, where we observed the most consistent cross-sectional flow. Mounting brackets are laser cut from 3/16” thick aluminum plate and CNC bent for perfect and repeatable fitment. Finally, heat shields are laser cut, CNC bent and hand assembled before going to powdercoating for a durable wrinkle black finish.

Performance

Dyno testing and long-term road testing are where all of this theory meets reality. Knowing that the same application of these design techniques resulted in intakes that performed extremely well on both the BRZ/FR-S and the 08-14 WRX/STI, we were confident in our chosen configuration. Dyno testing and tuning verified the intakes ability to make power and 6mos of road testing through winter/spring in Minnesota confirmed real-world performance.

We chose to use the exact same pull that tested the performance of our J-Pipe/Downpipe as the baseline for our 2015 WRX. This proves that our baseline is not somehow artificially low. We then installed the intake and had the car retuned using the same boost levels and air fuel ratios (AFRs). This is an extremely important part of evaluating an intake system. If the before and after results aren’t showing the same boost levels or AFRs, performance increases can be attributed to tuning rather than to the performance of the intake hardware itself. The chart below shows the before and after just described with both boost and AFR plotted along with whp and wtq. It should be noted that the stock baseline for this car was 174whp, so this particular dyno reads very low.



The GrimmSpeed intake produced an additional 32ftlb (14.3%) at 3000rpm and 21whp (9.6%) at 5500rpm, with healthy gains all the way across both curves. As mentioned before, the AFR and Boost curves are also included to demonstrate that the gains shown are from the intake alone, not the manipulation of other variables.

As with any intake for the 2015+ WRX, tuning is required after installation to maximize gains and safety.

GrimmSpeed Stealthbox Intake Kit Includes

  • 1x CNC bent intake tube w/ MAF flange
  • 1x GrimmSpeed high-flow air filter
  • 1x Aluminum heat shield
  • 1x 12" MAF harness extension
  • 1x Silicon hump coupler
  • 3x Stainless steel worm gear clamp
  • 3x Rubber gasket material cut-to-length
  • 2x MAF sensor machine screws

Options

While only a very small portion of the intake is visible after installation (nearest the turbo), we still decided to offer a color choice for the intake tube. The heat shield will always be our stealthy black wrinkle, but the tube can be either a matching black, or a wrinkle red.

** INSTALLATION NOTE - Take care to install the air filter onto the intake tube properly. Push the filter onto the tube no more than 1" before tightening the clamp. This will ensure that the velocity stack within the filter is allowed to function properly! **



average rating 5.0 out of 5
Based on 12 reviews
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100% of reviewers would recommend this product to a friend
Review posted
Reviewed by Mynor
Rated 5 out of 5

5 Stars

Muy tardado el envío

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Reviewed by Anthony K.
Verified Buyer
Rated 5 out of 5

Best intake in the fa game

Gs is best for fa. As always, iir sends it nearly immediately and got it super quickly. Highly recommend

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Reviewed by Mahase P.
Verified Buyer
Rated 5 out of 5

Much needed for the WRx

I added this intake to with my Grimmspeed Turbo Inlet and Grimmspeed BPV and the sounds are fantastic. In the process on being etuned for it and it’s worth the money, can’t believe I didn’t do an intake first. Just remember this intake needs a tune, and be careful when installing the factory scoop into the Stealthbox, I accident cut my rubber gasket but fixed it after taking the picture.

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Reviewed by Noel R.
Verified Buyer
Rated 5 out of 5

LOVE IT !

I don’t dislike anything about this intake love the color and LOVE THE SOUND ! Tuner recommended gs and a buddy of mine did too ! So I finally pulled the trigger and got one ! Install was pretty simple and I’m not one to install things on my car just your basic bulbs lip diffuser etc 😂

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Reviewed by Zach D.
Verified Buyer
Rated 5 out of 5

Stealth Box

Easy asf to install, recommend taking the scrape guard off when connecting to turbo inlet to get proper fitment. Sounds amazing!

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Reviewed by Kyler S.
Rated 5 out of 5

Best WRX Intake besides stock

I was skeptical about getting a CAI for the FA20 because of all the potential problems that may arise, but god damn is the sound amazing. If you’re going for power and overall reliability, just get a drop in filter and get it tuned. If you want loud turbo whoosh sounds that complement an aftermarket BPV nicely, this is the move.

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Reviewed by Kevin W., from United States
Rated 5 out of 5

Best of the best

Ive owned many different brands of air intakes, but this was my first time running a grimmspeed and I must say I am extremely satisfied. The throttle response increase is super noticeable and the sound is amazing! If you’re deciding between this and anything else, choose this.

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Reviewed by Devon, from United States
Rated 5 out of 5

Top Tier

If you want sound you got it.. If you want a hidden intake you got it. Overall best intake I've had. Air induction sounds great and quality of the product overall is 100% worth it.

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Reviewed by Matthew S., from United States
Rated 5 out of 5

Best intake for the 2015+ WRX

Your search for the PERFECT intake ends here. My induction noises are so satisfying it's orgasmic. Your tuner will also thank you "because it has a stopper on the MAF sensor flange to butt the filter up against. So everyone installs the filter in the same spot. All other intakes have "floating" filters, meaning that each customer can install the filter in a different spot on the intake pipe" (Ron Watson @phatbotti_tuning)

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Reviewed by Eli D., from United States
Rated 5 out of 5

Love it

Quiet when your cruising but roars when you want it to. Sounds great, easy install, and looks good.

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