As you might expect, Stage 2 remaps are more complicated than Stage 1 remaps and require intake/induction + exhaust, which may require an intercooler. By tweaking your ECU unit and adding minor upgrades like exhaust systems or larger intercoolers, you can significantly improve the performances of your car with far greater results than ECU remap alone.
 
Requiremenst for Stage 2:
*DPF, EGR, AdBlue Off, etc. (necessary on diesel engines)
*De-cat, OPF (necessary on gasoline engines)