AEM Induction 21-877C is a cold-air intake for Mazda 3 with the naturally aspirated 2.5L engine. The application-specific assembly uses gunmetal gray aluminum and an oil-free Dryflow filter. AEM reports an estimated gain of 8.97 HP @ 5209 RPM for its documented test configuration. Results are not guaranteed on every vehicle.
| Years | Vehicle | Engine / application |
|---|---|---|
| 2019–2020 | Mazda 3 | 2.5L naturally aspirated; exact manual |
| 2021–2026 | Mazda 3 | 2.5L naturally aspirated; current AEM finder, beyond the older manual |
This is not the separate turbo-engine intake. The older manufacturer-authored instructions cover 2019–2020; the current AEM finder also lists later 2.5L applications through 2026. Confirm the exact engine and configuration. The instruction prose contains K&N/Typhoon wording despite the exact part-number header and AEM filter; do not use that wording to substitute another kit.
| Detail | Value |
|---|---|
| Brand | AEM Induction |
| Manufacturer Part Number | 21-877C |
| Tube / finish | Gunmetal gray aluminum |
| Replacement filter | 21-203DK |
| Condition | New |
Factory sensors and reused vehicle parts are not supplied as new replacements. Refer to the exact illustrated parts list for individual hardware.
AEM Induction develops vehicle-specific and universal intake, filtration, and supporting components for street and performance applications. Black Ops Auto Works organizes each listing by exact part number and available fitment data to support accurate product selection.
What is the 21-877C?
The vehicle-specific intake described above; it is a complete intake configuration, not just a replacement filter.
Which applications are supported?
Mazda 3 with the naturally aspirated 2.5L engine; review the fitment notes before ordering.
Is the finish polished?
Gunmetal gray aluminum.
What replacement filter is listed?
21-203DK; verify the actual filter/kit revision before replacing it.
Is a new MAF sensor included?
The original vehicle sensor is reused; this is not a replacement sensor package.
Are the power gains guaranteed?
No. AEM’s published figures apply to its documented test configuration.
Does Dryflow require oil?
No. Follow the filter-specific cleaning procedure and inspect more frequently in dust.
What emissions conditions apply?
The current AEM page states that this kit is not legal for sale or use in California on pollution-controlled vehicles.
AEM instructions and illustrated parts list
California Proposition 65 Warning
WARNING: This product can expose you to chemicals known to the State of California to cause cancer and reproductive harm.
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