Air and Fuel› Air Cleaners, Filters, Intakes and Components
Perrin Performance
Perrin Foam Filter / Diffuser for AOS Bottom - 48ppi Red 2.5in x 0.825in Disc w/ Hole
SKU: P004 X-ASM-ENG-621
Easy — 1–2 hours
Description
Part #: X-ASM-ENG-621
MIA's Description
Fitment
Fitment Guaranteed
Don’t gamble
on fit.
Log your build in the MOTORMIA app and we’ll guarantee this part fits your exact setup — or your money back, return shipping covered.
Available on iOS & Android
Specifications
| Brand | Perrin Performance |
| Part Number | P004 X-ASM-ENG-621 |
Videos
Navigating AOS choices: Performance Vs. Pitfalls
PERRIN AOS INSTALL PART 2 OF 2 | 2015-2019 SUBARU WRX | AIR OIL SEPARATOR
FIRST ENGINE MODS! Perrin Inlet Tube + Filter 2017 Subaru BRZ
Perrin AOS Install GR86/BRZ/FRS
PERRIN AOS INSTALL PART 1 OF 2 | 2015-2019 SUBARU WRX | AIR OIL SEPARATOR
2022+ VB WRX Perrin AOS install the must have mod everyone needs
PERRIN AIR OIL SEPARATOR (AOS) UNBOXING | WHY YOU NEED ONE ASAP! | 2015-2018 SUBARU WRX FA20DIT
2022 WRX Perrin Air Oil Separator (AOS) Install (Plus charge pipe!)
INSTALLATION | PERRIN | AIR OIL SEPARATOR SUBARU WRX 2022 | 2023 | 2024
Boost Leak Be Gone!...Why You Need The PERRIN Turbo Inlet Hose For Your 22+ WRX
Buy with Confidence
Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.
View Full Return Policy