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Equal Length Header for 2002-14 WRX & 2004-16 STI


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Create a smoother sounding exhaust note while increasing horsepower with the PERRIN Equal Length Header

Equal Length Design

The equal length design of the PERRIN header, produces smoother more balanced exhaust pulses flow from the head to the turbocharger giving you the best of two worlds. Quicker turbo response as well as more horsepower and torque throughout the entire RPM band. While designed to fit to the factory up-pipe, our header will mate with an OEM or aftermarket up-pipe, as well as any rotated turbo kits compatible with the factory header.


You wont see grossly over sized tubing to make our header LOOK better as this just slows exhaust gases down and looses response. This header uses 1.5" primary tubing that is expanded at the flange to fit the Subaru exhaust port size. This size of tubing is perfectly designed for cars up to 400WHP. You can see from our dyno graphs that even on cars with well over 400 wheel horsepower there is a significant gain in HP and TQ across the entire RPM band over a stock header. For those looking to go way beyond 500 wheel horsepower, check out our Big Tube equal length header.

Flanges & Port Matching

PERRIN Flanges are CNC machined from 304 stainless steel and counterbored on the back side to make smoother transitions. Flange ports sized properly to ensure exhaust coming out of the head has a smooth unobstructed path to the tubes. The ports are not over ported which causes gaskets to burn out quickly.  


Because of it equal length design, the PERRIN header will alter the tone of your exhaust. The exhaust pulses from the engine are equalized and spread out producing a smoother, more refined sound. Some describe the sound to be EVO like similar to an inline four cylinder engine exhaust.
» Listen to the difference

Oil Pan

Most headers collect on the passenger side of the engine, and due to space constraints, are not equal length, compromising exhaust flow. Because we use the added room provided by the oil pan (only on 2.5L turbo pans), we can create a smooth transition of the header primaries to the collectors, and collectors to up-pipe, providing more power and torque then the competition. See our install kits here.


PERRIN headers feature a brushed stainless steel finish.

Jeff's Blog

Read Jeff Perrin's blog and learn why the big tube header was made and why it performs as well as it does. See it compared to our regular header and why you will need it for your big turbo kit.
» Learn More

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.
» Learn More

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
» Read Full Warranty

Warranty Exclusions

We will not warranty any exhaust part that fails or has warped flanges with header wrap installed. While header wrap protects the engine from heat as well as provides some performance benefits, it greatly reduces the life of any stainless steel part. Header wrap greatly increases the rate of corrosion (even stainless steel corrodes), added to that the actual temperature of the metal is much hotter, reducing its lifespan even further. Operation of vehicle without installation of splash guard will void warranty.

We will not warranty any flanges that are warped away from the weld if any aftermarket gaskets are used. Only OEM Subaru gaskets are to be used on this PERRIN Exhaust part, with the exception of downpipes for turbo kits. Subaru provides the proper crush gasket that still becomes flat when tightened (or over tightened) in comparison to aftermarket gaskets which can have a crush ring that is too think causing a hot-spot in the middle of the flange. These will warp the flanges of your PERRIN exhaust, causing a permanent exhaust leak that will not be fixable with a new gasket.


Warranty Details

This product features a 5 year warranty Read Full Warranty

Tech Department




Weight 12 lbs.
Material 304 Stainless Steel


Unequal length vs. Equal Length

In The Box

In The Box

(1) PERRIN Equal Length Header.
(1) PERRIN License Plate Frame

Dyno Charts

Dyno Charts

Proven Horsepower

Dyno Chart

07 STI Stock Header vs. PERRIN Header

This dyno graph shows what one of our customers found after installing our equal length header on his STI. The turbo spools quicker, the engine make more torque and horsepower over the stock header. As long as you are ok with the smoother quieter sound from the header, you will love the additional 20WHP and 30ft-lbs more tq! This test was also done on NASIOC in public forum comparing all kind of headers to one another. The PERRIN Header came out on top!

Dyno Chart

2.0L Stage 2 WRX vs. Equal Length Header

This test was done on our shop 02 WRX (aka Project 15K), and you can see that even on the 2.0L engine, the PERRIN Header is worth 10WHP and 15ft-lbs of tq. This test was done back to back in roughly 20minutes of work, so you can see the gains are very real.

Dyno Chart

GT3582R w/.82ar vs. Equal Length Header

This graph shows a customer of ours that had one of our rotated turbo kits installed with a GT3582R. Even on these larger turbos the PERRIN Equal Length Header also shows the same gains. The turbo spools quicker allowing the engine to make more torque (20-50ft-lbs) and in turn make more Wheel HP (10-15WHP).

Dyno Chart

GT3582R w/Equal Length Header Boost Curve

This is the boost curve of the same above car. You can see how much quicker the turbo spools up. The PERRIN Header reduces turbo spool time anywhere from 100-250RPM, making the car even more drivable.

Dyno Chart

05 Legacy GT vs Equal Length Header

Here is another test done on a Legacy GT. This also represents the 08 WRX models as they have very similar turbos and engines. In this test, the header was installed after a Stage 2 tune was done on the car, then after the header was installed, additional tuning was done adding to the 30WHP and 40ft-lbs of torque.

Compatibility Notes


2002-2005 WRX *Requires oil pan with header cutout and oil pickup tube.
2006-2007 WRX *Requires 2002-04 WRX oil cooler assembly and oil feed pipe.
2004-2008 Forester XT *Requires oil pan with header cutout, oil pickup tube, 2002-04 WRX oil cooler assembly, and 2002-04 WRX oil feed pipe.
2009-2013 Forester XT Yes, no modification
2004-2007 STI Yes, no modification
2005-2009 Legacy GT Yes, no modification
2008-2014 WRX Yes, no modification
2008-2014 STI Yes, no modification
2015-2016 STI Yes, no modification

See our install kits here.

*OEM parts

Oil Pan with Header Cutout Subaru Part #11109aa151 - Est. Price $108.28
Oil Pick Up Tube Subaru Part #15049aa110 - Est. Price $26.98
Oil Cooler Assembly Subaru Part #21311aa051 - Est. Price $219.95
Oil Feed Pipe Subaru Part #21317aa02 - Est. Price $43.38
O-ring (not needed unless damaged) Subaru Part #21370ka00 - Est. Price $5.82

header diagram

The PERRIN Performance Header not compatible with header wrap material. Using Header wrap will void all warranties. The PERRIN Performance header will not fit Moroso 20965 oil pans. Please call with further questions.



Keep in mind, these tests are ONLY for comparison purposes to help provide an answer to the question "How loud is this?" These tests are not saying any of these systems will pass any local law pertaining to a decibel limit for your car. If you are unsure of a system passing a local decibel limit law, please have a profession test your exhaust to determine if it’s legal.

Shipping Information

  • Item Requires Shipping
  • 19.0 lbs.
  • W10.0000” x H18.0000” x L38.0000”
  • This item ships in its own box.