Default [Q] Id like add new apps for all users on my tablets like sistem apps. its posible?

When I create new users, they can use all the stocks apps (Gmail, youtube, G+...). Id like to add more apps to use for all the new users ( f.e. file manager, titanium,...) and remplace the sistem app that I dont use for others more usefull for me.
I try to add one app to sistem/app, and I can find it like a sistem app with Titanium, but it not appear on the rest of the users...
How can I do it? is posible?

Nexus 7 with root and stock rom