Just last week I noticed the same thing...
It was sagging down about 4" in the middle.
I decided to take it down and found a mouse nest!!!
Decided to leave it off as others have done with NO I'll effects.
If I do replace it, it will be with one of these...
Aircraft firewall material hood liner pad for Mustang, Corvette, Grand National, many other cars
He uses aircraft quality material to custom cut his hood liners from.
You DO have to remove the hood to properly install the liner, but I think
That is a small price to pay to get the kind of quality this offers.
Even though he does not have onelisted for our trucks,
He can and will do one for the same price as the others, including
A large foil rams head if you like that sort of bling.
Personally I like the quality of these hood liners and the fact that
Mice will NOT be able to make anest behind them!!!