scraping noise under hard braking?!?!?!

hey guys, i have a weird noise coming from under my car during moderate to heavy braking... its kinda a metalic sound like something is rubbing or grinding. i have already just peeked under that car and no hard parts hang low enough to touch down . i even had a buddy lay on the ground while i drove by and slammed on my brakes a couple times and he said nothing was touching down on the asphalt..... but i still can hear the sound. all the brakes are new (about 3000 miles) and i their performance hasnt deteriorated whatsoever, so i strongly believe they arent the issue. i just wanted to know if any of you guys would recommend some areas to check when i get the car in the air this weekend to perhaps shorten my troubleshooting time. maybe its parking brake cables? exhaust? anything? i appreciate any input you can toss my way

well i gave the brakes a good look and the pads have plenty of meat still on them and the rotors looks good as new. . thanks for the idea... believe me i checked most things. i guess i need to get the car up about my head with my lift and check clearences on everything on the underside. i was just hoping to save some time if someone had an idea or similar experience. i am still open for suggestions though.. i wont be able to have a looksie till this weekend