Attention: TDR Forum Junkies 
Bob,
Of course, as you are suggesting, the owner/driver has no control over the egt of an unmolested engine, it is what it is. Where the pyro can be helpful though is if something does go wrong and where he normally sees around 1400° on a loaded grade when in regen but suddenly this time the pyro gauge pegs at 1600°. The driver with gauges sees it and backs out of the throttle. He has something to base his complaint on when he takes it to the dealer and runs into a dummy who tells him "we can't find anything wrong. "
As I posted above, I had that experience back in about 2002 with my old '01. The map sensor was bad. On a trip from Las Vegas back home pulling an Airstream I was down on power enough I could feel it in the seat of my pants. I could not attain full boost or normal max egt. The dealership dummies told me nothing was wrong with my truck. I went home and called Bill Stockard and Joe Donnelly. Each of them suggested map sensor. I went back to the dealership and told the then young mechanic what I had been told. I saw the light go on in his eyes. He understood. Thirty minutes later he was back in the service lounge with a grin on his face asking me if I was ready to take a test ride. He was proud to learn that lesson and fix the truck. He and I have been close friends ever since. He now owns that '01 Dodge that he maintained and repaired for me back then.
Gauges can't prevent mechanical problems but they can help the driver recognize them and argue successfully for someone to repair it.
Of course, as you are suggesting, the owner/driver has no control over the egt of an unmolested engine, it is what it is. Where the pyro can be helpful though is if something does go wrong and where he normally sees around 1400° on a loaded grade when in regen but suddenly this time the pyro gauge pegs at 1600°. The driver with gauges sees it and backs out of the throttle. He has something to base his complaint on when he takes it to the dealer and runs into a dummy who tells him "we can't find anything wrong. "
As I posted above, I had that experience back in about 2002 with my old '01. The map sensor was bad. On a trip from Las Vegas back home pulling an Airstream I was down on power enough I could feel it in the seat of my pants. I could not attain full boost or normal max egt. The dealership dummies told me nothing was wrong with my truck. I went home and called Bill Stockard and Joe Donnelly. Each of them suggested map sensor. I went back to the dealership and told the then young mechanic what I had been told. I saw the light go on in his eyes. He understood. Thirty minutes later he was back in the service lounge with a grin on his face asking me if I was ready to take a test ride. He was proud to learn that lesson and fix the truck. He and I have been close friends ever since. He now owns that '01 Dodge that he maintained and repaired for me back then.
Gauges can't prevent mechanical problems but they can help the driver recognize them and argue successfully for someone to repair it.
most big trucks do too. 
