Headers, Cats and Exhaust

[drmiles]

Ok, I'm ready to start upgrading my new H2.

I purchased Edlebrock headers, and new Cats and Xtreme flow exhaust www.xtremeflow.com.
I go down to my local exhaust shop and they tell me:
"Headers will burn up your cats"
"The cats you have are as good as they come"
"Any modification to the exhaust before the cats will void your warranty"

Is there any truth to these statements. Just want to get another opinion.