Originally Posted by woner
See if you can get a recording of the sound. I wouldn't think that the 135i and 335i would have different induction noises but it's weird that IancoleTX and I don't hear the same noises as some of you 335 guys.
I have had aFe on N55 335i and 135i, and BMS on N55 135i. They all sound roughly the same. There is a "wooshing" sound as the turbo just begins to spool, which sounds awesome. You can hear it very clearly in a dyno video I took with the aFe installed here.
From there up it's just normal engine noise and spool. It sounds awesome throughout the range IMO.