heh, I'm remembering more and more turbo stuff as I go on.
Are you doing any 'turbo timer' of any sorts? It'* important that you let the car idle and cool down the turbo a bit for a little while after a drive, the turbo timer is just like an inverse remote starter that lets the car sit and cool while you walk away. Temps are more finicky with a turbo than a blower I'd assume, always get up to full operating temp before boosting too, but I'm sure you know that one
How about "priming the turbo" on oil changes?