Agency Power 816CC Fuel Injectors (set of 4) Subaru STI

With the testing of our HUGE STI turbo kit, Agency Power needed more fuel to overcome the factory 550cc injector limitation of 350 crank horsepower. With many STI owners wanting to push the limits of their STI, more fuel delivery is much needed. With several different options available, Agency Power has just released 2 new options for STI owners wanting more fuel for their higher horsepower cars at an affordable price.

The Agency Power STI Injectors flow 816cc. These injectors are designed for cars with large turbo kits making 400+ horsepower. We have these injectors available as brand new sets of 4. You can also send your original equipment injectors to us at Agency Power for modification for a small fee. Mail-in injector modification receives FREE overnight return shipping. Modification turnaround takes up to 24 hours from the receipt of the injectors.

Agency Power recommends a larger fuel pump when paired with this injector upgrade to compensate for the fuel delivery needed. For any other questions about this Agency Power product, please contact us appropriately.

Notes on Installation:
The top of the injector has a screen covering the end of the port. This screen controls the fuel flow of the injector, as in the WRX blue injector it regulates flow to 420cc, the SAME injector with a pink body (STi) flows 550cc due to a bigger screen. Removing the screen from either will result in an injector that flows 720cc. on the side feed injector found in the USDM STi this same screen is used in the same manner, it is machined off the end to yield a flow of 816cc. the actual injection disk is not touched, metal from the machining process cannot get into the injector because of the design of the inlet screen, and because of steps taken during machining. The likelihood of an injector sticking open is extremely low. However the design of the side feed fuel system can lead to a massive fuel leak into the motor past the lower o-ring if it is not completely seated down into the rail. It will seal on the top, but not on the bottom, allowing high pressure fuel to get past the bottom seal and directly into the motor. A slight nick in the o-ring, contamination from dirt falling into rail from injector removal without first cleaning the site, or even improper lubrication while installing can also cause leakage past the o-ring. It cannot be stressed enough to observe proper procedure during installation, or better yet have them professionally installed to prevent leakage.


All Agency Power products come with a LIMITED LIFETIME warranty when you fill out this form HERE.