Hummer pro ? Hummer God is more like it !
You sound extremely knowledgeable. Were/are you a tech ? Your right about the pyrometer. Couple other things about the truck make us a little uneasy, some patched one of the fuel lines with a check valve and talking to a buddy of mine who is diesel mechanic has said this changes the timing and has an impact on how the engine will run. The previous owner must've had an auxiliary fuel tank and removed it prior to selling it,he/ they didn't plug the hole/s that were left from the mod and the first time we filled it up we left some fuel on the ground at the station. He is still mostly concerned with the engine repairs but will address this problem soon.