I finally got my EGT gauge installed just yesterday. Using a k type thermocouple into the exhaust manifold and hand held meter in the cab.

Interesting results, idle is around 140C, cruise at 100 km/h runs around 400. Highest is 680C which seems to be more a result of high intake temps (15 psi boost with no intercooler makes about 130C intake). Above around 12psi the hotter air from more boost seems to almost completely cancel the effect of more air which should cool the combustion.

But most interesting is after climbing a short hill at 4-500C, it takes only a few seconds to drop to under 200C. Makes me think a turbo timer isn't much use.