I've never fished Montauk before, but if it is like the rest of the spring runs... If the sun is shinning and/or really warm, griffith's gnats are killers. Try tying a large one 12 or 14 and tie a small 22 off the bend of the bigger one. If there only popping the big one, cut off the size 22 and drop off a zebra midge. Enjoy the day. That is my favorite winter setup for dries.
Another rig is I've read about but have not tried yet (can' t wait) is to use a large griffith's and a small bead head crackleback. After the float, swing them across stream. Again, I only heard it works. I've only fished small streams this year and there isn't a lot of swinging flies.