I have. I got under the car and had my dad hold it at 1500RPM exactly and there was no vibrations from metal or anything, he did the same while I held it where the sound happens. Probably the mufflers. I don't know if there's anything I can do about it? Seems to be coming from the drivers side only.

 

Very odd man.. Dont know what else I can really suggest.

 

idk exactly what sound your talking about but maybe your muffler is hitting the frame