Perrin designed this inlet pipe for the 2002-2007 Subaru WRX & 2004-2021 STI with two goals in mind. The primary goal was to make the pipe strong enough to resist sucking shut on even the largest of turbochargers. The other was to make the largest pipe that could fit in the narrow space available. Why are we so concerned about strength? If your setup is stock, there is not much to worry about at all. But if you are running higher boost levels, or larger turbochargers, the turbo can literally suck the pipe shut, especially if you are still using the stock airbox.
If you are planning on making more power out of your turbocharged car, you need to flow more air, period. Bigger intercoolers, turbochargers, and exhaust systems will not work if your inlet pipe is collapsing under the load. Perrin turbo inlet is the only one on The market to include OEM like connector that does not require defeating the emission control device
Fits 2002-2007 WRX and 2004-2021 STI (aluminum intake manifold cars)