So from what I've read online, Google interprets dashes in URLs as spaces making them better for SEO and readability - however, underscores are treated as hard characters.
 
Is it possible to change the underscores to dashes in friendly urls through ViArt or do I have to mess around with the apache conf file?

In 3.5 if you look at /includes/friendly_functions.php at line 126
"... ,"_" , $friendly_url);
.......^
the underscore can be replaced with a dash.
This seems to change the auto generated urls.
If you need to change existing "friendlies" I'm afraid its that leap back into the database.
 

Thanks Ned!