To me HP only counts where its useful - getting applied, & on a motorcycle simply put Rear Wheel Horse Power "RWHP". So reasoning is any HP loses before the rear wheel that are reclaimed is a up in HP. This picture is of the crank in my 2008-10 ZX10R crank that has had been lightened balanced & knife edged. The reduction of weight 900g reduces dead weight which restricts inertia acceleration. Motor speeds up so much more quickly whilst using less of the "BANG" in the cylinder which allows more bang (HP) to reach the rear wheel. During machining the majority of the weight was reduced from the counter weights & opposing shoulders to match the 1-10g weight tolerance in the rods & pistons. It all needs to be in tune. This crank was tuned for 14000 rpm = smooth so smooth almost vibration free power delivery. The knife edging often referred to as pointless & without benefit, is simply to allow the edges of the crank to spin with less surface contact on the oil mist in the cases resulting in less HP loss. I say a well sorted crank increases HP & improves delivery of the power.