i recently purchased the silicone snorkel tube from out motoring, and put a cotton filter on it. (I hate foam filters). Now I hear a hiss when on throttle slightly, or above 3000 rpm.
Is this normal? Or does it indicate a problem with the bypass valve. I know a "cai" will make more noise, I just didn't expect a hiss.

 

Normal.

 

The factory intake snorkel has been engineered to get rid of the noise...the ribs, etc did it...
Even some CAI intakes reusing the factory snorkel can cause a bit of a hiss at 2800-3200 rpm or so...
Just going to be a fact of life on a modded car...annoying things are engineered out and modding can bring some back in hopes of recapturing some of the performance gains lost to the compromises made to make the car "acceptable" to the most folks possible...