I washed the car at the local carwash yesterday and really flooded the CAI box and filter. Attached is what I did to maybe alleviate any future occurrences. I used 1/4-inch thick gray household sticky weather stripping as you'll see. It won't keep all the water out but should help.
Santa Elena Canyon, BIG BEND NATIONAL PARK, TX
2014 Mustang GT Premium black on black and blacked out... MODS: Sound pipe delete, tint and 1-1/4 inch Draw-Tite hitch receiver (the towing package)
I'd lose that covering & probably find another cars wash, my housing gets wet in rainy conditions on the hwy, but that is about it, and the pre-filter works fine. Also it can be dried off with a towel fairly easily if you have a screwdriver to remove the filter.
I doub't he is losing much if anything at all. Pre-filters are very common on ATVs and dirt bikes. They are nothing more than a water resistant light fabric and help keep the larger dirt and dust particles from clogging the filter.