i blew my header gasket that came with my bbk's and replaced it with mr. Gasket gasket's. they have metal in them and feel 10 times stronger then the bbk crap. no you dont need any sealer jsut the gasket.
I replaced one of mine with Fel-pro. No leaks. By the way I said I only replaced one. When you replace a header gasket should you replace both? I was running out of time after I had problems with the header flange comin apart at the welds and had to pull the header to get it welded.
definitely the metal gaskets and some stage 8 locking bolts. with this you should never have to replace the gaskets. i was having to replace gaskets about once a year until I got the stage 8 bolts. it has been 7 years and no leaks