Ren,
I've made an upper and lower shroud for my radiator for the express purpose to force as much air as possible through the radiator. It's made from sheet aluminum. Best way to do this is to make a pattern out of stiff paper or cardboard. Much easier to work with than the aluminum when you're trying to make it fit perfectly. Once the pattern is made, just transfer it onto the aluminum sheet, cut it out and install.
Jim
