Extreme PSI :: Air Induction :: Turbo Inlet Hoses and Pipes :: PERRIN Performance Blow-thru Boost Tube w/ BigMaf: Subaru WRX/STi 2002-2007

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PERRIN Performance Blow-thru Boost Tube w/ BigMaf: Subaru WRX/STi 2002-2007 #19974

PERRIN Performance Blow-thru Boost Tube w/ BigMaf: Subaru WRX/STi 2002-2007 #19974

PERRIN Performance Blow-thru Boost Tube w/ BigMaf: Subaru WRX/STi 2002-2007
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PERRIN Front Mount Intercooler users can now get a more accurate charge temperature reading and run a VTA BOV with no problems!  Instead of measuring the Mass Air Flow (MAF) and air temperature before the turbocharger, the PERRIN Performance Blow-Thru boost tube moves the mass airflow sensor to the boost tube before the throttle body.  The placement of this does many good things like allowing your ECU to read the actual charge temp the engine sees, which eliminates any need for aCold air intake (MORE IN FEATURES).  Also use our Vent to Atmosphere(VTA) Blow off valve with out running rich between shifts, or without idle problems. (see ASM-INT-600) 

The Blow-Thru boost tube also is designed with the Big MAF Intake in mind. Tuners around the world are familiar with this larger than stock MAF housing. This allows for the stock ECU to read more air flow, in turn allowing the tuner to tune beyond 550WHP! This also means the Blow-Thru boost tube needs to be tuned after installed. This part will not function correctly when installed on a stock tuned ECU.


The Blow-Thru Boost Tube is areplacement of the large 2.75” tube in the PERRIN FMIC kit thatrelocates the MAF sensor into the boost tube. The way the MAF sensorworks is very simple, and it doesn’t care, or know, if it is underboost or vacuum. This means the sensor can placed in the boost system,or in the intake system, and function normally.

Why do I want this?


The MAF sensor is normallylocated in the intake system before the turbo. In this situation, theturbo sucks in air, compresses it through the boost tubes, and into theengine. If there is leak in the intake system before the turbo (vacuumhose disconnected), it will cause the car to run lean and throw a CEL.If there is leak in the boost system after the turbo (boost hose loose,or popped off), it will cause the car to run rich and throw a CEL. Both situations are dangerous as they can cause sever engine damage.

With the MAF sensor located in the boost tube a short distance beforethe throttle body, any possible leak in the intake system will never bea problem. And being so close to the throttle body, most possible leaksin the boost system are not going to be a problem either. Also if youhave ever had a boost tube blow off and leave you stranded, that is athing of the past!


No more need for a cold air intake!  The MAFsensor not only has the airflow sensor in it, but the air temp sensoris also located in it.  With the MAF sensor/air temp sensor in theengine bay, it can read the high temps when your car is sitting still. Once you get going down the road, the temps drop significantly, butwhile waiting for your turn at the drag strip, or at a stoplight, theECU sees these high temps.  The ECU can then pull timing, and do otherthings that will hurt performance.  

A short ram style intake doesn’t loose power because the high tempsthat get into the engine, but rather from the high temps the ECU sees. At a stoplight, the high intake temps go through the intake, turbo,boost tubes, and intercooler before reaching the engine. The actualtemp the engine sees is nowhere near this temp. So the ECU is pullingtiming and changing fueling for no reason, as the engine doesn’t seethese high temps.  With the Blow-Thru Boost tube this all goes away!Since it is mounted just before the throttle body, it will read the airtemp the engine sees, and will make for more consistent tuning,driving, and power!


Another issue with Short ram intakes is that theMAF sensor is very sensitive, and things like fans turning on, and BlowOff Valves venting can change the readings of the sensor.  This causesthe car to run erratically in idle and cruise situations.  With theBlow-Thru boost tube, the sensor is located in a nice smooth straightpath of the charge air, which makes for consistent airflow.  Againmaking the drivability smoother, and more power!


The Blow-Thru Boost tube is designed using theBigMAF in mind. Since most every car looking at something like this hasan upgraded turbo, we decided to size the Blow-Thru boost tube the sameas our BigMAF intake systems.  The BigMAF intake system is designedwith a larger MAF housing than stock.  This allows the ECU to read moreair entering the engine, and allowing ECU mapping all the way to550WHP+. This size is also chosen as many tuners have maps built forthe BigMAF, and this makes for an easy transition from short ram toBlow-Thru.  This also means theBlow-Thru boost tube needs to be tuned after installed. This part willnot function correctly when installed on a stock tuned ECU.

VTA BOV Can be used!

One feature many people like is that aVent to Atmosphere BOV can be used with out the issues associated witha normal intake.  The BOV is normally located after the MAF sensor inthe boost system, and vents the air back to the boost system after theMAF sensor.  With a normal intake, it is important to keep the ventedair (from the BOV) in the intake system after the MAF sensor, so theECU can calculate the amount of air the engine is consuming.  If youinstall a BOV that vents the air to the atmosphere, it is like a boostleak, and can cause the car to run rich.  This happens because the airthe ECU thought the engine was consuming didn’t get consumed and extrafuel is added. This causes back fires, and during low RPM situationscan cause stalling.

The Blow-Thru boost tube relocates the BOV fitting before the MAFsensor, so none of these issues will affect the sensor, or how the carruns between shifts.  It’s a simple answer to peoples needs for a VTABOV!

CLEANER Intake path

Now that the MAF sensor is in the boosttube, the intake path for the turbo is much less restrictive. You couldliterally remove your intake from the turbo and it would still run!Included with the kit is an aluminum coupler to replace the MAF sensornow in the boost tube. This allows for great freedom with how and whatintake system you can run.  Again this small feature is another way youwill gain more power!

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