Originally Posted by greasemonkee

Honestly, I don't know if it's as simple as that. There are too many variables and it also depends on the engine.
The location of the egt probe is the first variable. Ideally, the probe should be half the runner diameter away from the head in the hottest cylinder. Naturally, the farther down you put it, the less it will read. I've always heard for hondas that full throttle operations shouldn't exceed 1250 and part throttle shouldn't exceed 1400-1500. The damage to components is likely cumulative. Take a look at the valves and seats of an engine that has run excessively retarded timing its whole life. The whole valve train will suffer and the springs will weaken over time. In my opinion, 1350 would be the max limit, especially for a boosted engine. Give it some timing or fuel and don't worry about the turbo, it should be able to withstand more than the engine.