Ive been getting a clacking/clicking noise coming from my engine at 3-6k RPMs, first noticed it driving, need to rev a bit higher while in the driveway/neutral in order to get the sound.... Im hoping this isn't a piston. Any other thoughts on this? started a couple weeks ago and hasnt gone away or gotten worse. Bringing it to the shop tomorrow.

http://m.youtube.com/watch?v=SnwPqQ9M55U