We designed our inlet pipe for the Legacy GT and Outback XT with two goals in mind. Our 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 on turbocharged Legacy models. 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. This situation is not only bad for power, but can literally destroy a turbocharger! Is bigger better?Yes! 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 simply suck in enough air.
That is why we designed our inlet pipe so large. So even if you are running our big and beefy AVO550 turbocharger, you will not be let down before the air has even reached the turbocharger!