Combine sugar, flour, salt, cinnamon and nutmeg. Toss with apples and arrange in unbaked pie-shell. Cover loosely with foil. Bake in hot oven (400'F) 50 to 55 minutes. Remove foil. Combine sour cream and 1/4 cup brown sugar. Pour evenly over apples. Combine graham cracker crumbs, sugar, cinnamon, nutmeg, and melted butter. Sprinkle over sour cream mixture. Sprinkle nuts atop crumbs and return to oven. Bake 5 - 7 minutes longer or till nuts and crumb topping are lightly toasted.