I think that the guys who said it did not affect the power had worn out engines.
I've seen that statement more than a few times.
With a fresh bore, piston, and rings I'm sure it felt just fine.
Let's look at Approx piston dome cc's.
Wiseco 3.25cc
Wossner 3.9cc
Stock 86 double ring 18.5cc
Stock 85 single ring 14.5cc
You can swap any of them around with the correct head and or cylinder cut.
But to think you can drop in a 3.25cc piston dome in a bike that was made for a 18.5cc piston dome and not loose any power...
Well... I could find some bridges to sell you