Perrin FMIC Black Blow-Thru Boost Tube Subaru WRX / STI 2002-2007

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The Blow-Thru Boost Tube is intended for use on Subarus which are using aftermarket turbo chargers that can "outflow" the stock intake system. It replaces a PERRIN front mount intercooler boost tube with one that is larger and accepts the factory MAF sensor, relocating it from the intake system to the the boost tube, allowing the ECU to read more air flow, in turn allowing the tuner to tune beyond 450WHP!

ECU Tuning

The Blow-Thru Boost Tube has a BigMAF built into it which requires ECU re-calibration in order to run properly on your vehicle. This BigMaf is designed to do two things:

  1. Allow your ECU to accurately measure airflow above and beyond what the stock intake can measure.
  2. It is sized specifically to offset the use of 800cc fuel injectors.

Eliminate Dangerous Leaks

Air leaks such as a disconnected vacuum hose or a loose or popped off boost tube are dangerous as they can cause severe engine damage or leave you stranded on the side of the road. The PERRIN Blow Thru boost tube moves the MAF sensor to only a short distance before the throttle body therefore allowing the ECU to compensate for any leaks in the system saving your engine.

Zero Turbulence

The MAF sensor is very sensitive, and things like fans turning on and blow off valves venting can significantly alter the readings of the MAF sensor. This will cause the car to run erratically at idle and cruise situations. The Blow-Thru boost tube locates the MAF sensor in a smooth straight section of the charge air, making a consistent airflow readings, improving drivability.

MAF Tube Size

The Blow-Thru Boost is designed with a larger pipe diameter right at the MAF housing. With proper tuning, this allows the ECU to read more air entering the engine without maxing out sensor voltage, allowing ECU mapping to 550WHP+. Tuners can start with maps built for the PERRIN BigMAF intake system, easily transitioning from short ram intake to Blow-Thru intercooler. This part does require ECU tuning and will not function correctly when installed on a stock tuned ECU.

VTA BOV Approved!

The BOV is normally located after the MAF sensor in the boost system. The Blow-Thru boost tube relocates the BOV fitting before the MAF sensor allowing drivers to use vent to atmosphere (VTA) blow off valves (BOV).

Cleaner Intake Path

Pro tuners now have the option of simply removing the Subaru intake and running a filter directly off the Turbo. No intake system is needed as the MAF sensor is now located within a boost tube.

Color Choices

This PERRIN Performance product features a durable powder coat finish. PERRIN powder coating is available in either red or black and is accented with a wrinkled texture finish.

5 Year Warranty

PERRIN Performance warrants to the original purchaser that all PERRIN products will be free from defects in material and workmanship within a sixty (60) month period from the date of purchase. *Some exclusions apply

Off Road Use Only

This product is legal in California only for racing vehicles which may never be used upon a highway. Check your local and federal laws prior to installation.


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