I dont hae a charger but mine does that under light load also. And it only started after i intalled the new Holley 68 mm throttle body. all the noise is, is fast air moving across the butterfly of the throttle body or something else along the way. I think it sounds pretty kewl. People look my way when they hear that whistling noise. lol
makes me want a blower for real. heheh

Matt