The Stainless Mesh filters do sound louder because they are more "raw", no sound deadening (bunch of holes) The cotton gauze/foam ones do a better job of muffling the sound, making a little softer in tone.

IIRC the mesh-type filters are loudest, flow the best, but filter the worst. IMO running a mesh-type filter would almost have the same filtering as running ITB's with straight velocity stacks.

In order of filtering ability, best to worst: Cotton Gauze, Foam, Mesh.

I have no idea which ones flow the best over time, but I do know the stainless ones are *supposed* to last forever without cleaning.. For the Cotton gauze or Foam ones, i'm sure the flow rate decreases a little as it gets dirty, but probably not much if you clean and maintain / buy a new one every so often when needed. The stainless mesh ones by design cannot filter much anyway, so there isn't much for it to be clogged with.. Which is probably why it lasts forever.

There was a test done a LONG time ago about the filtering ability of certain materials / brands, you should still be able to find it on the internet somewhere. Sorry, but right now I can't recall what it was called.

 

Its not the filter, its the shape of the intake. Sound waves get trapped (like in a silencer) different in different intakes. The filter may or may not increase the volume of the sound, but it doesn't really change its character.

jason

 

Yeah that too .. I forgot to mention that. Surely a stock airbox wouldn't have drastic noise variations just by the type of filter installed... But the filter does help a little!