Come on guys, give him a
break
but to answer your question,your post was a bit vague. Not sure exactly what you mean by "upgrade". Do you want new rotors, new pads, or a full on big brake kit?
Here is what I am planning to get when it's time to replace my brakes. Not really sure there are many more upgrades you can do short of a big brake kit.
EBC USR Ultimax Sport Brake Upgrade Pads Rotors SS lines fluid
You could also spend some extra money and get 2-piece front rotors, but I don't think anyone makes them for the rears