There will be very little in it between an Extreme map and the new stage 2 GIAC maps. The Extreme map is an older version of the stage 2+ map that is based on the larger MAF housing of the VF intake and uses MAF scaling in the map to work out what the engine needs in terms of fuelling etc. IIRC the VF intake is 70mm inside diameter and the std MAF internal diameter is 62mm?The maps roughly produce the same results and both have a pump version (using normal 98ron and above) or the race version (using WMI or race fuels)The race versions can produce even more bhp and lbft The stage 3 DSG map ramps things up a little more and the clamping pressure is elevated even more than stage 2 (I specified max pressure possible). Also the gearchanges are even faster at stage 3 than stage 2.
GIAC do a flashloader similar to Revo's SPS controller. It just stores the maps though and not the ability to alter boost, timing and fueling settings. http://www.giacusa.com/flashloader_handheld.php