F4i headlights have single direction reflectors which mean they EITHER point high or low. The problem with this is that when you switch to a dual filament bulb, you won't have a true "high" beam in the sense that it shines further. It may only shine brighter, depending on which bulbs you have.
You will need to make sure your high beam reflector is adjusted downward such that it doesn't blind people at night time. Instructions to do so are in your owner's manual and are very straightforward. Next you will need to find a way to mount H4 bulbs into your H7 reflector sockets. It shouldn't be too hard. You need to probably buy some H4 receptacles also.
The receptacles are the plastic things that plug into the BACK on the bulb before the plug that goes to your electrical system. They should be cheap.
Once you have the receptacles, you can go about splicing around. This diagram should help you, but I haven't done it so there are no guarantees. The worst that will happen is that you burn out a fuse. Check your F4i's fuses. If they say 10A you have a maximum of 120W lighting you can draw. More likely they say 20A and you can draw 240W total. You will need to account for some power spiking when you flip the switch, so a 20A fuse can probably only support 200W total power in reality.
H7's have two filaments: Ground, Power
H4's have 3 filaments: Ground, Lo Power, Hi Power
See below, goodluck. Let me know if it works! If not, you didn't get this from me.
