depends on your need and hunger of performance and power output..the more u modded (piston, valves, head etc) the less strength and durability of ur engine..
with some of modded 1000cc that has done by my workshop, it still running smoothly for two years but the idling kinda rough a bit due to high performance camshaft installed..how the engine withstand depends on your driving skills and habit..if u always force the pedal to the floor everytime and boosting higher everytime, then ur engine will also kaboom..frankly speak, even though ur engine is stock standard, it will never last for a long time if u force it everytime..
just to share the experiences