shadow walk/scape stealth level

i've a question: is shadow walk/escape stealth lvl increase passive?
i mean, with cat-like thread we can get stealth lvl = char_lvl + 20 at lvl 20
if i get shadow walk at lvl 10 and use shadow ESCAPE (that i've it at lvl 1), my stealth lvl will be char_lvl + 20 + 10 = char_lvl + 30?

if it is like that, if i have both walk and escape maxed, i would have as stealth lvl = char_lvl + 40 (20 from cat-like thread, 10 from shadow walk and 10 from shadow scape) b:shocked