06 6.0L Engine Noise at 2700 rom

[hitechmech]

Currently working on 6.0L that runs great until under load and above 2700 rpm then it sounds as if the valves are floating as popping noise through the intake and axhaust. Turbo has been iscolated as to verify not over boosting. Valve train visually looks ok, rockers,pushrods etc intack. FEAD belt removed. Fuel pressure fine. No codes. Customer has had the cyl heads and injectors replaced down country in march of this year. manual compression shows all cyl relatively the same 360 to 380 area. Relative compression all very similar readings. Unable to iscolate to any one cylinder but being as it happens at higher rpm is hard to iscolate Looking for any suggestions please

[Mekanik]

You mentioned that it sounds as if it is popping through the intake and exhaust. I have heard of some and seen one that was popping through the intake. I think either the intake valve was leaking or sticking. Can you determine if it is coming from one specific cylinder? If you were confident that it was popping through the intake, you could run the engine with the intake removed.

[hitechmech]

Two concerns found with this one, cyl 5 piston skirt damage and valves sticking on cyl 2 and 8. Now have to see how customer wants to proceed as out of warranty