Why is my cobra making a buzzing noise?

I have a 2003 mustang cobra with a ported Eaton and upgraded upper and lower pulleys. Recently there has been a loud buzzing noise coming from what sounds like the supercharger (i could be wrong though). it gets louder and changes pitch when the RPMs go up. At idle you don't hear the noise at all. i have already replaced the bearings in the idler pulleys and about to change the oil in the supercharger. if that doesn't work i am taking the supercharger apart, however i do not wish to do that. i would be eternally great full if anyone could tell me what the noise could be and how to fix it.