I tried to set the Decay to zero but the sound is still present. As you said duncann, it's a kind of whooshing. We can hear that sound better when I play with my seven string guitar, here's the recording (with Cubase). When I try to join the patch file, I get an error message. Basically, that sound appears on every heavy patch, and I'm always using Noise gate or Hardgate.
Riff 4.mp3