Air noise when muting?

I'd almost wonder if you have a dirty cable or contact or something, it's like the noise is actually louder than the distortion itself. I don't think gating that any more is gonna fix the problem, it'll just make the hissing stop sooner but you'll still hear it over the tone for sure.
 
you need to mute better yo, this is one of those "tone is in the fingers" things. try muting down by the bridge too with your palm, and when you mute the strings on the neck, use as much hand as you can as close to the nut as possible. the air noise you're hearing is basically a mild accidental harmonic combined with an amp tone that exploits it. try experimenting with both the technique and the drive/eq on your amp to see if you can find a combination that works for you to dial it out.