i have 2007 classic with 515hp ddec-5 and noticed i was loosing boost. Used to be 47 lbs under load and started lately to drop to max of 42 lbs. Did soap check on hoses and cac nothing found until soap from hose connection dripped onto turbo elbow and seems to be a crack at the seam of elbow. Welded back up and power come back. HOPE this helps others with EGR nightmares.