This is not exactly a cheat but it works. First go to options in the main menu and click on graphics card, Then click on the button below screen resolution then down the bottom it says "motion blur" and if you turn it on and use NOS the screen blurs like in 2 Fast 2 Furious.
Cheat Mode
Select the 'Statistics' option at the main menu, then press DELETE to return to the main menu. Then, type one of the following codes to activate the corresponding cheat function.
Simply stay behind a car and watch the points rack up.
Easy style points
After you unlock the oval drift track, go into "Quick Race" and choose that track. Then, race around it using the handbrake to powerslide into the corners. Depending on how good you are, you will unlock rewards every time you fill your meter, which does not take too long.
Shoot smoke from nitrous
To make nitrous shoot out smoke, put your car in neutral, or at the beginning of the race press [Nitrous].
Entering this cheats is the same as here standing above.
1998 Nissan Skyline GRT34
Select underground mode and complete at least the first 80 missions. A recommended car to use is the Acura RSX. You will then challenge Samantha. Defeat her under the medium difficulty setting and win the next drag race to unlock the 1998 Nissan Skyline GTR34.
Eddie’s: Nissan Skyline
To unlock Eddie’s car in the end, keep winning style points. Note: It is faster to win them in drift. When your style meter maxes out, a message stating that you have won Eddie’s Nissan Skyline will appear.
Use rims that normally will not fit
Certain cars can only fit so big of a rim. For example, the Miata can only fit 17s, but if you get a car like Skyline put 20s on it and trade it in for the Miata. The Miata will now have the 20s that the Skyline had in it. Do not try to install any other rims on your new car because rimms will go back to the maximum sized allowed.
Shortcuts
Look for alternate routes on your in-game map while driving. These can get you ahead of an opponent easily og shave off seconds on your timer. They will look like another road on the map, but sometimes are narrower. Most of the time these shortcuts will be hard to see or take, and can be extremely risky. At the beginning of the races that take place in front of the prison Samantha told you to race to for at reward, when the race starts, crash in the gate of the prison: It is an underground shortcut. Note: This only works after the race in which Samantha tells you to race to the prison in time for a reward.