in the rain would the ducted nose panel (the one with 3 slits on both sides) have an effect on the performance on the car, would it mess up the Air Flow Meter on the pop-charger?

 

I have one of those panels fitted on my '92NA and have not experianced any problems with it in the rain, when it rains here in Auckland it REALLY rains. Even when I have been following lage trucks on really wet roads and getting covered in spray it seems to have no effect. I'm pretty sure if you have a K&N type filter the oil will stop the water entering.