Just bought a secondhand DS4 and am all new to this (first car and last car Citroen saxo) it came with a RT6 sw RNEG 2.1 G 5. Obviously want to upgrade to get postcode functionality. Everything I have read says I need to get it configured after upgrade at a cost of £100. I have read through the forum and I'm still unsure what's best to do. What are the risk of upgrading to 2.86 without taking it to the dealer? What is the best method - direct or in stages? What the pros recommend? Any help would be greatly appreciated.