Master code: up, right, down, left, up, a
Every upgrade: up, left, down, left, up, a
Extra car mass: down three times and a
Boost: hold up and push a three times
Nicks coordinates: a, x, b, y
Impound garage cars: up, right, down, left, up, a

You must read below to do the codes!
You must press start and you go to the map and do the codes there.
They are to be done on the map only except for the boost must be done while in a car and driving.
These codes actually work so have fun.