Hope its not to late to throw my hat in the ring. I've been in heavy trucking all my life and my Cat and Cumapart engines havn't had the thermocouples in the exhaust manifolds since the mid sixties let alone has there been a gauge made since then with the warning colors marked for preturbo intallation. Maybe there is some new thinking that says its better. I don't remember exactly why, but there was a new way of thinking then that changed it from the manifold. It's all what you get used too. I have driven many miles in heavyhaul trucks that run at 90% to 100% all day long. You don't stare at any of the gauges all the time but rather scan them for abnormal changes. So lets say your pulling pretty hard and the temps are up there a bit, you don't want to look the gauge or gauges and have to add or subtract to be accurate while changing lanes looking for an exit or what have you. I can't think of anything that would out weigh one or the other. I've heard people say that with the thermcouple after the turbo you won't be able to tell if you blew an air charge hose off. I don't know anybody with a pyro and no boost gauge or the other way. In the large engines the turbos move so much air that they would have to blow a hose to raise the temp. noticably. And then you would have heard the loud noise and should have pulled over. On my powerstroke I don't even have a wastegate. I would think on our trucks you would notice lower boost and a strange noise from the engine bay. Bottom line, GET GAUGES, get familiar with them and what is normal. Keep your ears in tune when your work'n it. You can't go wrong.
