Quote:
Originally Posted by wdb
I was ready to believe it to be honest, possibly because of my experience with the STi. Subaru puts a baffle plate over the entrance to the downpipe, where it bolts to the turbocharger exit. That plate blocks off about half of the opening and strangles the engine at higher RPMs. A downpipe (+ tune to prevent leanout) on an STi is an instant 30+ HP increase, and can really be felt above 4000 RPM.
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Airflow math for force induction engine != Naturally aspired high revving I6.
That "baffle" that they speak of is the active carbon filter that sits in front of the paper element air filter. It actually doesn't restrict air as much as absorb unburnt fuel in the intake and prevents it from escaping back into the atmosphere. Removing the active carbon element in the airbox does NOTHING except making more induction noise available, which sounds nice.
Watch this if you want a semi-scientific research on how removing that active carbon filter affect real world results.
Gains are negligible.