About to cut the nose up to include an air intake to feed my CBR1000F engine. but what i really need to know is so i fit 1 naca duct (about 2" outlet or 2 of them. i am planning on an alloy fabricated air box so i dont suck in hot air from around the engine.

its a lot less trouble fitting just the one, but i dont want to cause a vacume for the engine.

Best method is to have a look at the bike's stock airbox and measure the area of the inlets on that, then maybe add a smidge just to be on the safe side.