There is no better Brake upgrade for the money than the Sport package brakes. These are still new so it might be really hard finding them used just yet. But for around 2K or less you can get them brand new. Best part is that all parts are OEM and easily found at ANY Nissan or Infiniti dealership!
PM me for ultra low pricing on the upgrade, we can take care of you if you decide to go this route.
The only other thing you can do for a full 4 wheel kit in this price range is simply to upgrade the rotors, pads, and lines. Not a Big Brake upgrade by any means, but approx $700-850 depending on brand etc.
I've done many Sport model upgrades, if you need to pick my brain a bit, just message or email me
