Instructions for Rotating the Subaru STI Intake Manifold

Parts Needed:



Gates K050340 Belt (1)


Throttle Body Spacer (1)


OEM Throttle Body Gasket (2)


Extended M6 Hardware (4)

Extended M8 Hardware (8)
Intake Manifold Spacer (2)
OEM Intake Manifold Gasket (4)


Step 1

Remove the intercooler, charge piping, upper intake manifold, TGV bodies, and turbo inlet tube as described in the factory service manual.


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Step 2

Remove the alternator as described in the factory service manual. Trace out the area on the face of the alternator from which material will be removed (circled in red); if you are unsure of where to remove material from, use the template included with your kit.



Fixture the alternator on your workbench (or mill) and remove approximately 7/32″ of material away from the face of the alternator. It is recommended (but not necessary) to use a mill to machine the alternator, however a 4 1/2″ angle grinder, pneumatic die grinder or Dremel tool will also work. NOTE: TO AVOID MACHINING THE ALTERNATOR YOU CAN USE A 2007 MODEL YEAR SUBARU STI ALTERNATOR.


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Cut or “notch” the bottom of the alternator bracket so the alternator can sit lower in the bracket. A 4 1/2″ angle grinder, pneumatic die grinder or Dremel tool will work just fine.


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Reinstall the alternator using the supplied belt (Gates # 050340). Check for adequate clearance from the A/C belt to the alternator (circled in red). Be sure that enough material was removed in step 2 to eliminate the possibility of the belt contacting the alternator.


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Step 3

Remove throttle body from intake manifold. Rotate the throttle body 90 degrees in the counterclockwise direction from the stock configuration, and re-install the throttle body using Full-Race throttle body spacer and extended hardware (M6). We recommend using new gaskets (Subaru PN#16175AA243) on both sides of the spacer to prevent any leaks.



Stock TB Configuration


Spacer and Gaskets installed

TB Rotated 90 Degrees and spacer/gaskets installed


Step 4

Place one Full-Race intake manifold spacer on each cylinder head as shown below. Use the included gaskets (Subaru PN#14035AA421) on both sides of the spacer to prevent any leaks. Next, carefully lower the intake manifold back into position with the throttle body facing the front of the car.


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Step 5

Following the instructions in the factory service manual, completely re-install the TGV bodies and the intake manifold in the rotated configuration.





This install should be performed by an experienced and competent mechanic. Before starting the engine, verify that all vacuum lines, fuel lines, and coolant lines have been properly re-routed, and that all electrical connections have been correctly re-established before moving on. Some of these connections may need to be lengthened, shortened, protected, or removed depending on your specific application.


It is recommended that the Full-Race reverse-mount intake charge piping and front mounted intercooler be used with the intake manifold in this configuration. Full-Race charge piping is specifically designed for this application and engineered to allow high velocity and minimal pressure drop of charge-air within the system.