You already have sways (if you didn't know that) You don't HAVE to, but getting sway bars that are larger in diameter than stock will greatly increase your handling and responsiveness. When upgrading sways, you should upgrade your endlinks as well. Ungraded sway mounts are also recommended but not ABSOLUTELY needed.
To answer your question, no you don't need to upgrade for the springs to work. That's what it sounded like you were asking.
A good read: