Hmm, I'm feeling a bit dumb here.
I'm trying to edit coins again.
1- I inserted the right amount of coins and did a XOR encrypted research. After some refines, I got only 1 result.
2- I found the XOR key and managed to change it in order to have 2700 coins (from 1439).
3- The value changes, but after I enter a race, finish it or exit from it, the value gets restored to 1439.
I've tried this many times, but nothing has changed.
The "strange" thing is that this value isn't truly encrypted, because its dword format matches the actual amount of coins (this is not true for tickets).
PS: I did the exact same thing one week ago and it worked just fine.