The Perrin inlet tube for the BRZ straddles the line between cosmetic and functionality for me. While Perrin and enthusiastic forum members would like you to believe this simple tube will add a few horsepower, the reality is less exciting as you’ll probably not notice any performance increase. However, it does make the engine sound better.
For me, the Perrin inlet tube’s biggest appeal is that it gets rid of the superfluous intake sound tube that Subaru and Toyota engineered for the FA20 engine. This tube pumps intake noise into the passenger footwell of our cars to “enhance” the sound of the 2.0 liter four-cylinder boxer motor.
I always found this sound to be a little artificial and unnecessary after installing my Nameless Axelback exhaust. Deleting the factory sound tube also did wonders to clean up the engine bay.
Subaru and Toyota aren’t the only ones guilty of pumping additional sound into the cabin. The new BMW M3 and M4 feature “Active Sound,” which amplifies natural engine noises and plays it through the stereo. Even the 2015 EcoBoost Mustang does this. Apparently automakers think enthusiasts like cheesy amplified engine notes.
Perrin claims the 0.3″ increase in diameter and the tube’s more gradual curve is good for an additional 2-4 horsepower but that amount is so miniscule, you won’t feel it. I’m using the stock intake with an APEXi drop in filter and noticed no performance increase.
However, I do appreciate Perrin’s attention to detail by adding stainless steel rings inside the tube’s silicone body. This prevents the tube from compressing or collapsing under vacuum when the throttle body is wide open.
The Perrin tube is also completely smooth inside, unlike the stock one which features a bunch of accordion wrinkles for wiggle room.
And of course, Perrin stands behind its product and offers a five year warranty for its intake tube.
Installation of the Perrin inlet tube is simple. The single hardest part of the install is removing the sound tube, which spans across the entire passenger side of the engine bay. This took the bulk of my time, and resulted in me sweating profusely trying not to destroy any of the factory tubing. I accidentally yanked too hard on the tubing attached to the front right strut tower and pulled off the entire length of tubing leading to the firewall. I then used the included cap on the angled plastic tube protruding from the firewall instead of where Perrin intended its customers to cap the excess sound tube, which is near the strut tower. Oh well. I shave off an extra six grams of weight by removing even more useless tubing.
After the soundtube and stock inlet tube are removed, the rest of the installation is a breeze. The only issue I had with the Perrin tube is that clearance is pretty tight with the stock airbox. If you’re using the Perrin inlet hose with their intake, the inlet tube will be rotated clockwise, giving you more clearance from the serpentine belt.
I’m running the stock airbox and have about 7mm of clearance. Still, this tight clearance hasn’t given any issues. I’ve been using the Perrin inlet tube for over 500 miles and there has been no rubbing or shifting.
With the Perrin tube installed, I was struck by how much quieter the car is, especially at low RPMs. There’s still a surprising amount of intake noise when you’re at wide open throttle so I’m not sure why Subaru and Toyota felt it necessary to engineer a soundtube at all. The engine sounds so much more natural with the Perrin inlet tube installed.
If you’re thinking about getting the Perrin inlet tube for your BRZ/FR-S/GT86, get it because you want to properly delete the noise tube. Don’t get it thinking you’re going to get a noticeable jump in power.