The nords from skyrim are inspired by the vikings, and i was thinking that the vikings used blowing horns a lot, so maybe in skyrim you could use a horn to create a supershout, there are plenty of things that you can make a blowing horn out of in skyrim, and realistically speaking it could add like 50% to shout power.

Shouts are an unbalanced advantage only really available to you.
Don't need them stronger than they are.

they are totally useless at higher levels, so i think that having stronger shouts could make them somewhat useful at higher levels

Disarm isn't useless to me, nor is dragonrend at higher levels. I think of them more of a strategic tool then a powerful kill spell. I think what difficulty someone plays at also comes into play whether you use shouts regularly or not.

Ice Form is useful at higher levels

but what about all the other shouts, they took a long time created all the shouts, so why make them useless after you get passed level 40

^Ah yes Ice form, what a great thing for archers who get surrounded by a few too many melee's.

The fire and frost breath shouts are absolute garbage. They don't do enough damage relative to their cooldown times.