Mapped to Stg2+ and engine built at Stg3+ and 40k miles
Bigger turbo etc....head built at around 60k with around 500bhp
Cylinder head journal failure at 80k miles,but no sign of that until.....
Engine stripped down and rebuilt at 80k miles plus head work
Now at 550bhp/550lbs and 90k miles.
All internals found to be within tolerances,inc crank etc
I think if the engine is properly built and maintained,reliability is not an issue,but rapidly becomes a serious risk if all servicing isn't done regularly and to a very good standard.