Hi
If I get you right you want to have a blank before each
capital letter except the first one in the string. Right?
If yes use

$s =~ s/.(?=[A-Z])/ /g;
[download]

si_lence
update:
The comment of edan is right (sorry to mess it up)
but this should work

$s =~ s/(.)(?=[A-Z])/$1 /g;
[download]

si_lence