Here is a pretty cheap way to protect your radiator and oil cooler cores on Nismos. The last track day I was getting a huge amount of track debris coming at me and also caught a small sparrow that came in through the front air scoop and ended up with his head sticking out my front passenger wheel liner.
I got all the supplies form Custom car grill.com for about $60. I ordered the large hex screen powder coated gloss black.
I took the front off the car to this but I think you could do it with it on ramps as long as the front was higher than the rear of the car.
With the screen you order a rubber border which I used when I was laying it up for the patteren so it wouldn't scratch the paint.
The to horizontal 1/4 inch masking tape was used to mark the edge for the cut. I did one side at a time fitting and trimming until I got what I wanted..
And a couple of shots of the finished product. This looks pretty good but, is mainly for track use for radiator protection. For 60 bucks not to bad.