The statement "how long does my engine last when I chip it" can't be said in miles/km, because a engine does not know the term miles/km. If a M124 operates on the potential of a 30d, but you never or only rarely request the full power, the life expectancy won't change at all. If you floor it a lot and request the full power often, it will come to slight structural changes. Depending on further circumstances your engine can fail after a few minutes, or maybe 1.000 operating hours.