I upgraded my Fg rear brakes to Territory over easter. Using T3 discs, QFM pads front and back and braided lines all around. It has made a very noticeable difference.
Pulls up about 15 metres shorter from a 100ks, but very noticeable at normal town driving. People say " spend the money on the front" as it does more work. But before you do take a look at the rear set up. Smaller disc, not vented, not grooved, far smaller pads and calipers. Yes does less work and was designed to do less. Upgrade the front and leave the factory rear and you will be putting more strain on the already undersize rears. When the front discs need replacing I will be putting T3 on the front.