I was checking everything out while I was under my new 00 excursion v10 my clamp that holds muffler to cat was broke amd pipes are loose. I saw there was no post cat O2 so I am thinking of gutting it. Does it help the v10 exhale better? Or is it tempermental to back pressure?

 

I might help, it might hurt, and will definitely be the "wrong" thing to do in any case

Removing the cat can help the exhaust tone. But I still wouldn't want to do it, just in case you get a visual emissions inspection, or worse, get stopped by a state trooper who checks everything

 

I would fear obnoxious exhaust sounds, as well as the typical stink of no cat cars.
You will NOT find any noticeable power improvement by gutting it. These are very, very high flow cats.