I agree with teh guys for the most part.

Reuse bolts
Reuse stock head to manifold gaskets
New catback gasket
I don't care for the clamps they give you. I prefer to get 2 2.25" and 2 3.00" clamps from frozenboost at $5 each. Much better clamps for slip fit headers. They won't put an indent like the clamps supplied. When you have to pull apart the headers it'll be much easier.