If you're really worried, you can install a bypass filter in the winter months. When the main filter gets soaked, air is drawn through the bypass filter instead, air being easier to pull than water. The only problem is that you are still pulling some engine bay air at all times, so there is a power loss. I find it best to only use the filter in winter, and remove it in summer.AEM
has one that fits between sections of the Intake
, but there are questions about its safety -- apparently the foam can break apart and be sucked into the throttle body.
The other option is to use a valve blowoff filter. These are cylindrical little filters, usually 45mm across with a small fitting extending down from the center. A hole in the CAI
pipe at an appropriate place in the engine compartment will allow you to insert the bypass filter. The better bypass filters have a flanged rubber stem, which makes it easy to insert. The other advantage to one of these filters is that in summer, a rubber strap is all that's necessary to close off the hole. With the AEM
, you'd have to remove the CAI
to pull the filter.