MISHIMOTO TV Installation

Sound Testing for the Mishimoto Cold-Air Intake Compatible With WRX STI

The Mishimoto CAI makes great power, but it also creates excellent engine tones that will make customers very happy.

To test this, Mishimoto engineers placed AKG Acoustics' studio-quality, cardioid condenser microphones around the Subaru with and without the CAI installed. Recordings were made taking special care to keep the input gain levels, microphone placement, and all other recording conditions identical from one run to the next.

The recorded sounds were analyzed to compare the relative decibel strengths across the entire bandwidth of frequencies. The red lines in the graphs below represent the maximum volume achieved for each frequency band during the entire dyno pull.

A note about frequencies: The range of human hearing is typically about 20 Hz to 20 kHz. The majority of the fundamental frequencies fall between 20 Hz and 5 kHz. As a point of reference, some common sounds and their approximate frequency ranges are listed below.




Thunder: 0 Hz to 200 Hz

Male singer: 100 Hz to 500 Hz

Female singer: 300 Hz to 1 kHz

Lowest note of a bass guitar: 100 Hz

Jingling keys: 1 kHz to 5 kHz

Male singer: 100 Hz to 500 Hz



The Mishimoto CAI had the most notable volume gain in the 40 to 160 Hz range, which provided the intake with the additional 'growl' that was missing from the stock intake. Substantial volume increases also occurred at 125 Hz and 250 Hz, providing the intake with some additional low-end resonant tones and contributing to the 'throaty' quality of the sound.

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