does it refer to A) running lean, or B) stressing the turbo? just wondering.

 

Out of context, I am not sure, but you can never run a diesel too lean. You can, however, over-speed the turbo, or just set the turbo up so that you are running more boost than necessary, actually raising your pre-turbo EGT's without any more efficient fuel combustion.

 

thank you for clarifying that for me.