You just need the bigger rotors, dual piston calipers, and caliper mounting brackets, and brake lines for those calipers. And of course brake pads.

here are a couple other upgrades.
this ones some serious stopping power cts-v brakes.
http://www.dsmtalk.com/forums/showthread.php?t=218171

This is with Outlander Rotors
http://www.dsmtuners.com/forums/articles-suspension-brakes/428973-05-06-outlander-bigger-brake-upgrade.html