Add Istanbul and valencia circuits in GP.
Make backup and replace files accordingly. May corrupt saved games and not for online.
If you have installed 5 tracks mod http://www.racedepartment.com/downloads/5-additional-tracks.3668/updates, use the database.bin in "database 2+5 tracks" folder instead, else the 5 tracks will not be available.
As the tracks were designed for previous game versions, the performance and fuel usage are most likely inaccurate. Please do not ask me to edit them. There is no racingline also.
NB Please do not use one shot quali and flying lap for the tracks as you will literally be flying.
Edit: Turn off safety car