Flashing the ECU:
For reading and writing to your ECU you need a specific interface. There are some cheap parts available such as Galletto-Clone or MPPS.
For the latest 2.0JTD in 159 and Giulietta you will need a more expensive tool: KESS V2
Giulia & C0. up to now only can be read/write by openeing ECU with a tool like this: Ktag
With the interface you can read the binäry file from your ECU (there are the Maps and program code stored).
Then you have to edit the relevant Maps and flash back the file to the ECU.
Be sure your batteries are strong!!
For details visit the sub-pages.