Could it be the pulleys?

Well after I had my intake and headers put on my car has been idling a little low, so now when I come to a stop at a red light or whatever it drops to .5k rpms and lower and I can hear what sounds like a metalic high pitch rubbing sort of noise, now I know I need to replace my belts because they squeek every so often but this sound comes from the same area, but its not the belts. Now if I give it a little gas to around 1k the noise fades away. So if it is the pulleys I would rather just replace them with aftermarket ones instead of just turning up the idle so I cant hear it anymore. Any suggestions or opinions on the problem would be great.