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Old 12-05-2012, 02:41 PM   #561
Scooby Newbie
Member#: 256924
Join Date: Sep 2010
Chapter/Region: RMIC
Location: Little Rock, AR
2011 2011 STi
Dark Gray Metallic


For those of you just looking for that Tssss or Chufff sound when you come off the boost, the easiest, cheapest (free) way to get you 70% of the way there:

Remove the white plastic resonator from your factory intake airbox. It will amplify the sound of your stock recirculating BPV by close to a factor of 10, sounding like a slightly muted VTA BOV.

Advantages (over a VTA BOV):

*FREE upgrade you can do in your garage with very close to 0 skill and only basic tools.
*Does not cause any performance problems.
*Does not require a Speed Density pro-tune to function correctly, since all the air metered by the MAF sensor is eventually used up by your engine.
*Your OEM BPV doesn't leak (if you are getting a turbocharger capable of boosting high enough to cause a leaky stock bpv you will need a protune anyway)
*You can hear the whine of the turbo compressor clearly.
*You can hear the WHOOSH of air being sucked into your intake under boost.
*The rest of us won't be mocking you for making your car WORSE just to hear it breathe.
*Unlike most aftermarket intakes, you won't need to reflash your ECU for it to work properly.


*Not quite as loud as a VTA (though for many people it's loud enough)
*If you are eager to spend your hard earned money, or charge up your credit card for parts you can't really afford (most of us have been there), installing a ~$250.00 TiAL or equivalent quality BOV, and getting a high quality ~$500.00 Speed Density (MAP Based) pro tune will net you considerable power gains (from the tune, not the valve) without running rich, in addition to having a louder noise - whereas removing your resonator will not make a difference in power.

While running rich is not going to blow up your engine, it will result in less power at partial throttle, and wasted gasoline. A "Speed Density" tune uses information from your MAP (manifold air pressure) and temperature sensors to infer mass flow rate of air into your engine. This allows your ECU to account for the air vented to the atmosphere by your aftermarket BOV.

Going to a full VTA BOV without a Speed Density tune is like removing your car's hood to save weight, without replacing it with a lighter CF one. I mean... YES, removing your hood altogether WOULD save weight, BUT it causes other problems - and announces to the world around you that you have no idea what you are doing.

Whatever mods or parts you choose to bolt onto your vehicle, know how they will affect other systems and why - and consider all your options.


A lot of folks who buy and install VTA BOV's erroneously see it as a good starter upgrade without needing a protune. Please don't be "that guy". Try the simple solution first, and if that doesn't satisfy, at least do it right and get a good SD protune to go with the valve.

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Last edited by Street_EJ257; 12-05-2012 at 11:28 PM.
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