Engine sound changes at 3000rpm

With spirited driving my ZR TD sounds raspy at 3000rpm, but only around there, higher it sounds normal, and lower it sounds normal.



Is this the EGR valve opening as I read on here that it changes the engine note when open to metallic sound which could be used to describe the sound my car is making.



But would the EGR even be opening at those revs?

from the last news http://ift.tt/1mky084

via IFTTT