A while ago I posted on Western Subaru Club about the GP Moto elbow and how it affected the STI boost/airflow.
This time I decided to test the stock intake, complete with the resonator, against the modified version that I have been using for the last few years. It replaces the resonator with a “velocity stack”, otherwise also known as subwoofer vent flare.
It can be bought here:
or here:
The stock intake system:
After making some baseline runs with the modified setup, I re-installed the resonator and collected several runs. This was done without taking the car off the dyno. I had intended to test the AEM intake after this but the 3rd gear in my transmission decided to call it quits and killed itself :-\
Install pics
Power/Torque
Red is the modified intake, Blue is the stock setup with the resonator.
Boost/AFR
AFR was richer by ~2% with the resonator in place and there is a clear reduction in horsepower output above ~5000rpm.
Additional data from 07 STi, May 17th, 2011
