Engine help

This may sound strange, but here it goes...

My car sound like it has a supercharger.. but i don't. At first i thought it was transmission wind, but it isn't, i put it in 'N' and 'P' and when u rev it some, it will start to sound like a supercharger, and we all know what that sounds like, my check engine light came on maybe a few weeks after i noticed this. Im wondering what it could be, the real reason i asked, is when i was backing in my inclined driveway a few mins ago, while the winding sound accrued, it sounded like something was scraping in the engine, so bad, i could feel the vibration in the gas peddle. I also still have GM warranty, so i am going to call in the next day or so. Just wanted some ppl that know theses cars input.

Thanks

Going to bed BUMP

Post up the sound its making and we can help you further..
Any mods?
Loose vacum line? Bad bearings in pully? small exhaust leak? the list goes on and on. A sound clip would help up a bunch..
J