nah muffle doesn't stack .. if you have an item that gives muffle, casting the spell doesn't do anything further. --- Antec 900 II, Intel Core 2 Quad Q6600 Kentsfield OC 3.40Ghz, Asus P5N-E SLI motherboard, Thermaltake 800W PSU, EVGA GTX470 SC Edition, 6042MB DDR2 RAM
and the perk doesn't do anything unless you are making noise in the first place. --- Antec 900 II, Intel Core 2 Quad Q6600 Kentsfield OC 3.40Ghz, Asus P5N-E SLI motherboard, Thermaltake 800W PSU, EVGA GTX470 SC Edition, 6042MB DDR2 RAM
From: DylanX570 | Posted: 1/26/2012 12:13:44 AM Muffled Movement gives you 50% muffle, and I believe enchanted Muffle Boots give an additional 50%.
Yup. Once you get 100% muffle, going higher makes no difference.
100% noise reduction: Silence perk Muffle spell Ebony mail (only while in sneak mode) Light armor boots named "Predator's Grace" which you can get inside Hag's End (never seen these myself but the wiki says they are there)
50% noise reduction: Muffled movement perk Any self enchanted muffle boot Shrouded boots/shoes (including ancient type) Cicero's Boots Jester's Boots 2nd tier of Nightingale boots
25% noise reduction: 1st tier Nightingale boots
And then of course there are the 3rd tier Nightingale boots (level 32+) that have a bugged enchantment that gives +35 points of muffle which translates into 3500% noise reduction.
Lots of discussion as to what has what level of muffle items have and tests run on it's effects here: http://uesp.net/wiki/Skyrim_talk:Muffle_%28effect%29 --- http://i41.tinypic.com/rsvioo.jpg