My exhaust has been making noises around 2 to 3 thousand rpm's for a while now, and it is finally starting to get to me. I can't tell exactly where it is coming from on the car, but its more of a buzzy rattle that only will happen while accelerating, and will go away over about 3000 rpm's. Any ideas on what it could be??

 

Is the buzz mixed in with rattling from metal to metal contact?

 

If you have the stock exhuast it may be going out (buzzing) , rotting away, or your exhaust hangers my need replacing (rattling). My Maxima had a bees in the can noise and actual metal to metal rattling, but this was after I installed a y-pipe. I wrapped the pipe with header wrap for the buzzing and bent the heat shield by the gas tank back some, as well as the bracket/heat shield that is right above the catalytic converter.

 

Check that heat shield on your cat. Could be your muffler rustin' apart inside too. Good excuse to upgrade!