If your pollen filters look like the below picture its time to act
A critical area of importance to take note of and act on is the fresh air vent intake system, usually there is what seems to be a foam type of cover mounted from the inside part of the grill, this foam piece is a disaster zone as it's not compatible with the harsh work it has to do.
Pic below shows where it all ends up, note how its blocking up the water channel.
Ever got into your P38 and wonder why it smells and feels so damp.......as the picture below shows the foam that was originally placed just on the inside of the plastic grill piece is no longer.
Note: There is a join in the channel to the fire wall, this join faces up and even though it looks flush its possible water may enter through this wide section, sealing up is a simple task using a good quality non acid releasing silicone.
Since doing this my left foot well is dry
Another very easy simple mod is to drill or slot the pollen filter covers, this will allow water that gets past the seal to drain away instead of making its way through the filters and into the cabin area
Pictures below are from a scrapped P38 and pictures were taken for illustration purposes
This picture shows another potential water entry spot (Left side)
View of drain hole from vent grill area, note debris build up
and some more...