I agree with Troutman. I have caught fish in the park on everything from 3x-6x. I have never used 7x there b/c I usually fish a 5wt rod and it's too difficult for me to not break 7x on a 5wt when I set the hook. I would say that the majority of my fishing in the park is 5x whether nymphing or dry. I always make sure my 5x tippet is flouro when nymphing. I have experimented a lot this past year on the Davidson in N.C., and I feel like 5x flouro catches fish as good as 6x mono does. I like to use as heavy as I can get away with in the park, b/c you never know when that 25" brown that just got posted on here might take your fly. I wouldn't want that fish on my 5wt with 7x. Well, I take that back, I wouldn't mind that fish on my 5wt with 7x, I would just feel a little better if I have my usual 5x on.