How does gear enchanted with +sneak improve sneak?

For example, does it increase by percentage your sneak skill, or is there some hidden behind the scenes value that is increased instead?

For example, with 5/5 in Stealth and a sneak skill of 80 is your skill effectively 1.4 x 80 = 112?

It modifies the Skill.

I hate math.

If your skill is 86, and you have gear that adds +3%. It will get a 3% increase to that number.

Ok, that said, does a sneak skill over 100 make any difference?

I misunderstood the question some.

The perks for sneak is a hidden modifier.

%modifiers from gear however is show as buff(it will be colored green).

I don't know if sneak above 100 will make any difference.

It improves it by improving it. Really.
I can't get into the math or science, but I can definitely say it heavily improves the sneakability of my heavy armor wearers.
I mean, it's still possible, but the eye is a lot smaller when I alert stuff by hitting stuff.

For buffing your sneak skill over 100 with enchanted gear, yes it gets buffed - SneakMod will show the amount. But whether or not it is necessary is another question. There are a bunch of modifiers which are applied to whether or not you will be detected while sneaking. But what I would guess is that there will always be a random chance in there of being detected. ie: You may have a character build that can often go undetected, but it will never be able to be undetected 100% of the time. Therefore my theory is if you cannot be undetected 100% of the time, the more you alter the existing modifiers in your favor, the better off your sneaking will be - at least until you hit some point of diminishing returns.

I can say I have no difficulty sneaking. It's not so overpowered that I don't have to think about it, which would detract from my game imo, but I do feel pretty safe sneaking around. Here's roughly what I have:

100 Sneaking skill.
+47% self enchant on boots.
2/5 Stealth perks in the Sneak tree.
Muffled Movement perk in the Sneak tree.
Muffle self enchant on boots.
Conditioning perk in the Heavy Armor tree.

I've doubled up on some stuff, but with the movementnoisemult I still only have .5 *shrug*

I think some of the multipliers that determine whether or not you'll be detected involve the complete weight of your armor and your speed which are applied to your movement noise plus how visible you are (line of sight, amount of light, your perception condition (?) etc), and of course your sneak skill which seems to be able to have 2 mod values applied to it, which I'd assume will still get applied even if the skill is 100.

Any clarification on these would be welcome.