*if u would happen to do it exactly in my dimensions/placement of vent*
then the rain is no biggie...the hood opening is right at the mouth of the fan shroud so it gives the engine a nice mist during rain when motor is running and when sitting, just drips of plastic fan blades. once i get elec fan it wont touch a thing dripping in, driving rain will still mist obviously. $60 for hood, 20 for materials to cut/bondo/fiberglass it. directions are here:
http://www.240sx.org/links/installs/hood/hood.htm