I have a set of BBK Long Tubes and O/R H Pipe. This is all. I need header gaskets, fasteners, O2 extensions, and MIL eliminators. Is this all I need? Do I need O2 extensions?
I would re-use the stock gaskets, unless they are shot. Mine were fine at 75K miles. Re-use stock studs/nuts. You need some O2 extensions if I remember correctly. I used my Predator to turn rear O2 off even though I have the short catted H pipe. If you are planning gears, then the handheld tuner is the way to go instead of MIL elims.
I thought I remembered reading somewhere that only the 04's need the extensions when installing longtubes and a new midpipe. I think it might have read it on Ninosport .
dont buy the extensions, just go down to the autoparts store and get some 14 ga wire and extend them yourself. Solder the connections and you will be fine. This is a great way to keep the cost down.
Like BCB00GT said, if you can reuse the stock gaskets, go for it. Whatever you do, don't buy them from ford, they are an incredible rip off. Summit sells them for like $20 for the set. I also took some Red RTV sealant and put a thin bead of it around there, the last thing you want after all that work is to find out there's an exaust leak and have to tear it apart and do it all over again.
Good luck with the install, and yes, the O2 extensions (or equivalent) are a must.