From the Telegraph.co.uk, By Kevin Ash:
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...the V-twin was in the wrong state of tune, with its power concentrated at high revs at the expense of torque in the low and mid-ranges, where it's really needed on this type of machine.
The new Stelvio addresses that problem, with the help of Aprilia engineers, who have fitted a new camshaft and airbox and revised the engine management. The result is a boost to the mid-range at the expense of 3bhp at the top end.
More info linked on pic below: