They come pre-gapped. You can check to make sure they are o.k. I used a 28 thousandths wire and a 32 thousandths wire for go-no go checking. All were fine.
They are not meant to be re-gapped and can be very easily ruined by trying. If the gap ain't right (not likely), get some that are.
I got mine (NGK Iridium IX) from the local O'Rileys Auto Parts Store! Cheaper too than any of the internet vendors I had checked.