I remember the first time we had one in for mapping and it was also the first 1.9pd we had seen with the EDC16 ECU system so was all a bit new, however mapping it was great fun purely for the achievable gains from some very basic mapping. Soon after one of my mates bought a 1.9 105hp Caddy van and we set about tuning that, he wanted as much power as possible, so we developed our stg2 software on his van. Then another mate bought a mk5 with the same engine and wanted stg1 which he was happy with, but was back within a few months tempted by stg2.
Our Stg1 (+35bhp and 40ft/lb) and 2 (+50bhp and 65 ft/lb) are both software only upgrades, stg3 is available but requires a lot of ecu components.
Many will say that the stg2 power hike is too much for this car/engine but both of the above vehicles have covered 20k+ miles with no problems whatsoever, so dont be scared off by the big power hukes that these engines can achieve. The most important aspect is the torque delivery, it should be smooth and progressive through the entire rpm range rather than all coming in at once and peaking at 1800rpm.