Sorry, what i meant in my previous post was if you drill holes into it then water can enter the filter.
If you went through a deep puddle for example then on the induction stroke the water would be sucked into the combustion chamber and then when the piston come up on the compression stroke instead of squashing the air/fuel mixture it would be attempting to squash the water (Water will not compress like fuel/air) and then your engine Hydrolics
and breaks a conrod or a crankshaft.
Potentially very dangerous.
I was dashing out to work this morning and didnt really have the time to explain fully.
Is your air filter a Dry
type filter or is it oiled ?? If it is a dry type filter then if you drilll holes in the cover or remove it then it will absorb the moisture when raining and cause a damp air intake causing very poor performance, however if it is a Wet
type filter then as long as the filter is well oiled the oil repels the moisture and allows a dry air intake.
Hope this makes sence