AEM 21-833C Cold Air Intake System

Why Upgrade Your Civic Si with the AEM 21-833C?

Because the L15B7 turbo wakes up FAST with better breathing.

The 21-833C delivers:

• Increased airflow compared to the restrictive OEM box

• Sharper throttle response in every gear

• Stronger mid-range and quicker spool

• Aggressive turbo + induction sound, especially under boost

• AEM Dryflow filter – washable, reusable, oil-free

• Powder-coated aluminum intake tube that looks as good as it performs

If you want your Si to feel quicker, louder (in a good way), and more alive, this is one of the best bolt-on starters.

This Performance Air Intake System allows your engine to breath more air compared to the restrictive factory air intake housing. It is designed, tuned, and dyno-tested to produce more horsepower and torque.

Key Features of the AEM 21-833C

🌀 Mandrel-Bent Aluminum Intake Tube

Smooth internal surface with a diameter engineered for stable MAF readings.

❄ Optimized Cold-Air Placement

Draws cooler, denser air from the front of the engine bay, improving consistency under boost.

🧼 AEM Dryflow Filter

• Washable

• Reusable

• No oil

• High filtration with excellent flow

🔧 Direct Fitment

Uses factory mounting points and OEM sensor locations. No guessing, no cutting.

🎧 Turbo Sound Enhancement

Makes every spool, chirp, and bypass noise 200% more addictive without making the car obnoxious.

The cone-shaped AEM Dry flow air filter is made from an oil-free, synthetic filter media that can be used for up to 100,000 miles before cleaning is needed (depending on driving conditions).

What Kind of Gains Can Civic Si Owners Expect?

Typical results include:

• Faster throttle response

• More mid-range torque

• Quicker turbo spool

• Better airflow for tuned applications

• A deep, sporty intake tone

Pair it with a downpipe, intercooler, and a hondata tune, and the Si absolutely wakes up.

A custom shaped heat shield with edge trim lining is included to keep engine bay heat from the air intake.

Daily-Driver Friendly

You get all the fun with none of the headaches:

• No tune required (but strongly recommended for maximum gains)

• Dry filter = no risk of oil fouling sensors

• Works flawlessly with factory ECU logic

• Maintains reliability and fuel economy unless you drive like a maniac — which you will, obviously

The air intake tube is constructed from mandrel-bent aluminum featuring a durable gunmetal gray powder coated finish.

Installation Overview

Expect 45–90 minutes with basic tools.

1. Remove the factory airbox and intake plumbing

2. Install heat shield and mounting hardware

3. Bolt in AEM’s aluminum intake tube

4. Attach Dryflow filter

5. Transfer MAF sensor

6. Tighten clamps

7. Fire it up and enjoy turbo noises

No cutting. No drilling. No swearing (well, not much).

This air intake system is backed by AEM. Some AEM air intakes are not legal for sale or use in California and other states adopting California emission standards, while others are 50 state legal. View the vehicle applications to determine the legal status for each vehicle.