A NA engine will loose power with altitude however a blown engine either turbo or supercharge will be the opposite. Even a rajay system which provides SL conditions at altitude till it gets to critical attitude when performance is lost. These engines are fitted with auto controllers to compensate. At the end of the day the person behind the controls can make or break an engine weather it is running lop or rop.
And not one engineer I know would let a cly out with 5/80 and an exhaust leak.
Cheers