Genki Gremlin Decoration:
Hold R2 when choosing your shift assist option. Keep the buttons held until the game has competed loading. The Genki Gremlin will be hanging from the roof of your car in the first person view.

Blue Mosquito Decoration:
Hold L2 when choosing your shift assist option. Keep the buttons held until the game has competed loading. A blue mosquito with yellow sunglasses will be hanging from the roof of your car in the first person view.

Dog Decoration:
Hold L1 when choosing your shift assist option. Keep the buttons held until the game has competed loading. A dog with horns will be hanging from the roof of your car in the first person view.

Man Decoration:
Hold R1 while selecting a transmission type. Keep the R1 held until the game completes loading to see a man hanging from the roof of your car in the first person view.

Pink Creature Decoration:
Hold R1 when choosing your shift assist option. Keep the buttons held until the game has competed loading. A pink creature will be hanging from the roof of your car in the first person view.

White Carismo Car:
Defeat the last Zodiac (White Carismo) to unlock his car and get about $4 million dollars. To get $5 million dollars when you defeat White Carismo, let him win the first time he challenges you. Then go up, challenge him, and win. At the ending you will see a message appear that saying "Challenge Ending = 5 Million Dollars".

Skyline Car:
Defeat the Speed King to get $3 million and unlock the Skyline car for purchase.

Display Replay Meters:
During a replay, press Select.

View One-on-one Battle Positions:
During a one-on-one battle, press to see the positions of all other cars.

View Free Run Positions:
At the course selection screen in free run mode, press to see the other cars.

Control Replay View:
Start a replay in the driver view position, then press L1 or R1 to pan the camera.

Fixed Replay View:
Hold when the replay is about to start.

Full Pause Screen:
Pause the game and press + . Press + again to restore the pause screen.

Delete Scores:
At time record screen, hold L1 + L2 + R1 + R2 and press Start.

Analyze Option:
Pause the game immediately when you start a drive in quest mode. Scroll all the way down the pause menu to access an "Analyze" option under "Retire". This allows you to see the turning rate, accelerator, and brake pressure. This only works at the very start of the drive and you cannot turn it off once enabled. Note: This may be dependent on the car type or parts.

Free Rims Anyone?:
Go under were you can choose your rims and don't buy the brakes kust go to the rims you want and go down to either plate or colored and chose whatever color you want and go to equipt.

GameShark Codes

(M) Must Be On
EC85E4301456E79B 
  
Max Cash
4CA25EAE1456E79C
 
P1 Inf SP 
0CF70C261456B00B
1CE48B2014921C65
   
P1 No SP 
0CF70C261456B00B
1CE48B201456E7A5
   
Opp. Inf SP 
0CF70C261456B00B
1CE48B2414921C65
   
Opp. No SP 
0CF70C261456B00B
1CE48B241456E7A5
 
Max Total Miles
0CE48F3E1456E7A7
4CA25EDE145630A5
  
Quick Mile Gain
0CE48F3E1456E7A7
4CA25F881456B00C
 
999 Days
0CE48F3E1456E7A7
4CA25EAA1456E404
  
Always Control Car 
4CE3A4A81456E7A5
Overtake your opponent before the race even begins.
 

Thanks to Revolution reader Speed Racer, Lee&Kris, stefan roetz and m22intexas!