finally getting around to installing a header i purchased on ebay several years ago... want to say it was a pacestter but cant remember.jeep is a 96 with the 4.0.any tips or suggestions i should look for or address while im in there ? header came with a gasket . should i toss and buy another ? what about upgrading the fuel injectors . 6 or 4 hole? will i need to take to muffler shop afterwards or do most line right up with existing exhaust ? just pondering before i get started .

I think I would try to find a Fel-Pro gasket for that, it is a job you won't want to do twice.
Here is a link to a video that is about 30 minutes long on changing out the exhaust manifold.
Hope this helps...