you are describing exactly what I experienced. It's throttle position, not RPM where the noise happens.
It's really easy to get to. I just had to take my air box off. It's kind of near the alternator but down a little. he says to "disconnect the battery for safety reasons" well ya..but it's really so your computer can re learn the new EGR. So before you start, disconnect negative terminal, do swap. Snug everything bag up, re connect and you'll be good to go