First post so be gentle

I am getting the X5 re-mapped on Saturday, the question I have is this- Is the OEM Braking system still up to the job or does anyone recommend upgrading the Brakes too?
Would this just be a change to the Discs and Pads or include the Calipers too? I do like the idea of a nice shiney Brembo Caliper sat in behind the wheel but I am not sure if I can justify (well I can to myself, so I guess that's all that matter lol) the high price tag! Would I just need to upgrade the front brakes only or do the rears need doing as well?
Cheers
Garry