Bikes using detuned sportbike engines?

Some bikes use detuned sportbike engines. For example

1)The FJR1300 uses a detuned R1 engine

2)Street triple uses a detuned daytona engine

3)Honda Phantom TA150, a 2 stroke cruiser uses a detuned NSR150 engine

Is it possible to 'retune' these engines so that it churns out the same level of power & performance of the original sportbike? Or is it too elaborate a job involving more then just tuning - changing ECUs, CDIs, remapping, sprockets etc

Sorry if its a dumb question

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