I'm not sure I understand the question. Enchanting perks, Magicka, skill level... none of that governs what you find in the game world.
The muffle effect from enchanted items you make will always be the same magnitude no matter what level you are. The Muffle enchantment will always be at a maximum value of 1.0, which is the equivalent of 100% or completely silent.
This holds true if you disenchant them. The effect will be applied to the new item at it's maximum of 1.0 no matter the size of the soul gem.
Enchanting another pair of boots, using a petty soul gem will yield the same magnitude as using a grand soul gem.