I have a question. I know how the BOV works. I installed a K&N panel filter and this noise got louder. And I hear with an intake it gets even louder. So question is... why is it getting louder with a free-er flowing intake?

 

the stock BOV is a recirculating valve which dumps the air back into the intake tube with an open element filter (cone or even the panel filter on the stock box) it becomes more noticable. you should be hearing your turbo spool alot more along with the BOV.

 

So then it's really just causing an amplifying affect? It's not really more compressed air getting re-circulated that is causing it to get louder.

Also so then the X recirculates the air and doesn't dump it to atmosphere?

 

no the Evos run a recirculated system. unless you tune it on an AEM standalone or Speed density it will be recirculated. the K&N or similar filter will allow more air to flow through which in turn will make things louder. it actually makes the car sound better

but if you havent done so yet, do a boost leak test and make sure that you do not have any leaks. thats peace of mind

 

OK. Yeah I knew the air flowing made it louder when then throttle is open. And yeah sounds better! Was just trying to understand why the recirculated air was louder.

 

It's not louder, per se. You can just hear it better with a less restrictive filter.

 

^this. It will be louder with an open filter due to not having the intake box muffling the sound, you'll also get the added bonus of hearing the turbo spool.