Problem is ST170's are now getting within the price range of young kids so instead of most 170's being well looked after serviced etc they are now being owned buy kids who dont look after them and rag the shit out of them which will end in problems. Mine has oil and filter changes every 1000miles, is maintained regardless of cost and never misses a beat, apart from the clutch i have not had one problem with it in 3 years.
They can handle a turbo producing over 300bhp on stock internals, to me thats a strong engine