if your doing it yourself, make sure you remove your original exhaust studs. you WILL NOT be able to reuse the nuts on the the back side of the manifolds... with
bbk headers, the nuts would not fit on the studs... i had a NASTY exhaust leak for a long time. I have since switched to stage 8 locking fasteners, and have not had a problem since. They are around 50 bucks and well worth it... i had several nuts on the original studs come loose and you will find out very fast how un-easy it is to install everything...
make sure that you drop the k-member and use an engine support to do the job, otherwise your going going to be VERY unhappy with the results. Its a very time consuming project... but IMHO its worth it in the end.
i suggest,
stock exhaust gaskets, or percy's seal for goods
stage 8 locking fasteners
02 sims
after market H pipe (sounds better than x imo)
new hardware for the midpipe
and a tune...