I thought about this for the front doors when I was working on mine. I didn't have the time to do it, but I was going to cut out the plastic grill (easy to do) and form a perforated metal grill to fit in it's place. I did a search on google for perforated metal and found some stuff that would work. I'm not sure if you have to buy in bulk or not though. Seems it could be possible, with some tin snips and a ball-peen hammer, and a wooden block to make some. Paint covers the rest and makes it look stock. They do sell the thin gauge perf sheet metal. I guess it depends on if you have the time or not to work it.
JE
