Revup, Uprev is tuning software, confusing I know.
I wouldn't bother with the 2005 GT4 model, unless it's near the same price as another 2005. If it was a 2006 Revup it would be a different story because there are additional changes to the car other than just the engine.
As for parts for the GT4, the only difference will be for a plenum spacer, I think you also need to buy a MREV2 lower plenum to go with it. Induction kits and exhaust components are all the same.