In terms of kcals per gram you can't get a much better ratio than you do with Super Noodles.
Expedition foods make some good dried meals that you just pour hot water into, they have more protein than a Super Noodle, which might be a consideration on a longer trip, but no real difference in kcal/gram. They feel a bit more like a proper meal, but cost £4.00+ instead of 50-80p. I don't use them anymore. You can always take a pepperami or similar to add protein.
What I do take now are packets of noodle soup from Chinese shops. They are bigger than Super Noodles, and have more dried veggies in them. Still very cheap at 55-85p, easy to cook, and the same kcal/gram.
To boost calorie density in a dried carb based meal, the only method is to add fat. Add a thick slice of butter to pasta, noodle or cous cous. Or take olive oil in a light plastic bottle. Makes it taste better too.