Think he's just wondering why you're taking it to the dealer when you just had an aftermarket turbo and pump installed at another shop. Why not take it back to the shop, have the oil and coolant changed, make sure the reservoirs are full, and see if that solves your issue? That would be my first step. You just paid for install of these parts, make sure the shop makes good on it.
Truck is still at shop that done upgrades for me. But after what has happened and comments I read, his knowledge of 6.7 is questionable. Would rather have experienced mechanics assess the situation. I though shop I took it too was experienced in 6.7 but after all this has happened he admitted he only worked on 6.0 and 6.4.