Hi Alan.
Remove the wing plenum tubes and cut the flap off, reinstate and you will find the water will flow more freely and will not block up.
The two plenum tubes in the bulk area, on under the ECU and the other under the brake servo can also be cut off but only from under the car, I did this way back in 2010/11 I also do it if I have to get under any members car for any reason, once this as been done the plenums should never flood or even get enough water in them to wet the pollen filter ever.
