Biggest problem with a cone filter and no airbox with fuel injection is getting an accurate and consistent air temperature reading for the ECU. In addition you'll have to fabricate a mudguard and something to fill the gaps to stop crud getting everywhere you probably won't save much weight anyway! Also in my experience (even with carbs) removing the airbox seriously robs your motor of torque in the low and mid range. The only bikes I've ever found that improve when removing the airbox are carb fed 2 strokes, but i'm more than happy to be proved wrong...