I have a 1992 LX Mustang with the 5.0, can I run open shorty headers?

What is your question?

I have heard some say you can warp or crack the valves running the car with open shorties, and have also heard people say you can put an old rag in the end of the headers. I am concerned doing this, could it catch fire since the headers will be extremely hot? I understand you definitely do not want to do this in cold weather, but would any harm be caused running it in the summer with temps in the 70-80's? Any advice, please let me know!! Thanks Noah