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GrimmSpeed StealthBox Cold Air Intake – 2015-2021 WRX

GrimmSpeed StealthBox Cold Air Intake – 2015-2021 WRX


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



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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.


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.

As with any intake for the 2015-21 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 dry 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

** 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! **


Additional Information

Intake Tube Color

Red, Black


  • 2015-2021 WRX


Installation Guide

Install Guide